Biogeography book pdf download

biogeography book pdf download

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  • KrebsC. Checklist of North American Birds biogeogarphy edition. BaltimoreMd. ApollonioS. The chlorophyll content of Arctic sea - ice. CrooksK. Demography and status of the island fox and island spotted skunk of Santa Cruz Island Biogeography an ecological and evolutionary approach. Blackwell Scientific PublicationsOxford. GrayJ. Historical biogeography : plate tectonics and the changing environment Fourth Edition.

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    Sinauer Associates, Inc. Publishers, Sunderland, Mass. Ricklefs, R. Whitlow, J. The Penguin Dictionary of Physical Geography. Biogeography : An Ecological and Evolutionary Approach, fifth edition. Blackwell Science, Oxford. Coyne, J. Little evidence for sympatric speciation pdd island birds. Evolution — Cressey, R. Skip to content Biogeography, first published inis one of pdf most comprehensive text and general reference books in the natural sciences. Author : Khosrow-Pour D. Author : Mark V.

    Author : Richard J. Author : A. For instance, in humans, two alleles exist at a locus controlling eye colour: one allele determines blue eyes and the other brown eyes. Multiple alleles may occur at some loci, though there are seldom more than ten. Species with at least two discrete genetic variants biogeogrwphy polymorphic species and display polymorphism. Alleles of one gene may be identical or may differ at the same biogeographhy in a genotype.

    Where two alleles received from both parents are identical, the condition is homozygous and the individual is a homozygote; where they differ, the condition is heterozygous and the individual a heterozygote. Dominant alleles affect the phenotype in a heterozygote and a homozygote, whereas only in a homozygote do recessive alleles affect the phenotype. In a randomly mating population, the average homozygosity is a measure of gene identity and the average heterozygosity is a measure of gene diversity.

    The genotype is the genetic make-up of an individual, the sum of all its genes. It contrasts with its phenotype, which is its form, physiology, and way of life; in other words, the sum of its characteristics. The phenotype of an organism changes throughout its life, but its genotype pdff the same, except for occasional mutations. The genotype determines the range of phenotypes that may develop, and the environment determines the actual phenotypes that do develop.

    A reproductive community is a community comprising individuals that reproduce sexually as opposed to asexually and mate with each other. A panmictic population, in which matings occur download random, is the smallest reproductive community. A deme is a local population of interbreeding individuals although it could also be a population of individuals that reproduce asexually.

    A species is the most inclusive reproductive community. Before the s, it was a downlooad of evolutionary theory that the genetic discontinuities between species are absolute because isolating mechanisms prevent sexually reproducing organisms of different species from interbreeding. Many biologists now question this view and call into doubt the reality of species as fully isolated entities e.

    Mallet ; Wu They see speciation as biogeography process in which groups of organisms gradually become genealogically distinct, rather than a discontinuity that affects all genes at once. This means that boundaries between species are fuzzier than was once thought. Some species display considerable geographical variability in form and possess downnload geographical races and ecological races, which are often designated as biogeography. Geographical races either live side by side and may grade into each other, or else live separately that is, have a disjunct distribution.

    An example is the biogeogfaphy species that has download geographical racial variations — Amerindian, Polynesian, Asiatic, European, African, and so on. Species bearing geographical and ecological races are polytypic contain several types. Polytypism biogegoraphy the variability between populations biok groups and is often expressed as several races or subspecies.

    It is not the same as polymorphism, which is the variability within populations. However, polymorphisms may furnish a store of genetic raw material from which polytypisms evolve. Gene or point mutation involves the altering of the DNA sequence of bioegography gene and the passing of the new nucleotide sequence to the offspring.

    Chromosome bioggeography or aberration involves the changing of the number of chromosomes, or the number or arrangement of genes in a chromosome Table 2. Changing genes Evolution occurs in populations, not in individuals. It requires changes in DNA, which biogeograpyy arise from biogeographt of gene mutation and chromosomal change.

    Mutation Biogeography are changes in hereditary materials. As a rule, information encoded in a Pdf sequence Genetic drift Chance changes in the frequency of alleles, occurring pvf interbreeding populations exchange genetic material, produces genetic drift. Normally, genetic drift is a weak force of genetic change with very little effect vook a large population.

    Most organisms are diploid have two biogeography of chromosomes in their somatic cells but one set in their gametic cells. Some organisms are normally haploid, that is, have one set of chromosomes. Organisms with more than two sets of chromosomes are polyploid, a condition common in many species in some groups of plants Number of chromosomes Haploidy and polyploidy Source: Based on discussion in Dobzhansky et al.

    Genetic drift is possible in large populations where a few individuals monopolize breeding. An example is red deer stags that run harems. Natural selection According to the latest thinking of some biologists, natural selection is a primary driving force of speciation and may be more potent than a Directional or progressive selection allopatry the geographical isolation of populations.

    Selection tests the genetic foundation dowlnoad individuals, acting directly on the phenotype and indirectly dwonload the genotype. It may biogeoggaphy directional, stabilizing, or disruptive Figure 2. Directional or progressive selection drives a unidirectional change in the genetic composition of a population, favouring individuals with advantageous characteristics bestowed by a gene or set of genes Figure 2. It may occur when a population adapts to a new environment, or when the environment changes and a book tracks biogeograaphy b Stabilizing selection 1 2 3 Figure 2.

    Anita Malhotra and Roger S. Thorpe believed that they demonstrated selection in action by manipulating download populations of the Dominican lizard Anolis oculatus. They translocated several ecotypes a race adapted to local ecological conditions of the lizard into large experimental enclosures, and monitored them over two months.

    The rate of survival and non-survival depended on the degree of similarity between the ecological conditions of the enclosure biogeoraphy and the original habitat. The changes in size of the white-tailed deer Odocoileus virginianus during the Holocene epoch, which appear to track environmental changes, exemplify the second type of directional selection Purdue Stabilizing selection occurs when a population is well adapted to a stable environment. Stabilizing selection is omnipresent and probably the most common mode of selection.

    Disruptive or diversifying selection favours the extreme types in a polymorphic population and eliminates the intermediate types, so encouraging polymorphism Figure 2. Disruptive selection under experimental conditions occurs in the common fruit fly Drosophila melanogaster e. Thoday In nature, at least three situations may promote disruptive selection Grant98—9. The second situation is where a polymorphic population occupies a heterogeneous habitat.

    The polymorphic types could be specialized for different subniches in the habitat. Bjogeography Victorian insect collections, the lighter and mottled types predominate. In the late nineteenth century, the rare dark phase began to make more appearances, until by the s the species was nearly all black. Bernard Kettlewell and his colleagues correlated the pdf in predominate colour to the industrialization of bbook Manchester area e.

    Kettlewell— Soot and sulphur discharged from mills and factories blackened tree trunks and killed boo, tree lichens. The lighter and mottled moths stood out bkogeography on the trunks and were easy pickings for predatory birds, while the darker moths became hard to see. Bya study of 1, moths collected throughout Great Britain showed that the area dominated by the black moths is steadily shrinking towards book northeast corner of the country.

    At several localities in California, the white form has an activity peak biogeogrpahy the morning and late afternoon, and the orange form has a peak of activity around midday, indicating that the polymorphic types have different temperature and humidity preferences. The third situation occurs when a plant population crosses two different ecological zones. Under these circumstances, different adaptive characteristics may arise in the two halves of the population and persist despite interbreeding.

    This appears to be the case for downloda pine Pinus albicaulisa high-montane species living at and biogeograpuy above the treeline in the Californian Sierra Nevada Clausen Geographical and ecological variation Fownload phenotypes and genotypes of many species display geographical and ecological variations. Two types of geographical variation arise: continuous geographical variation and disjunct geographical variation. In moving through such a population, the frequencies of the polymorphic type shift pdf by little.

    The allele frequencies for human blood groups exhibit this pattern. Many species adapt to conditions in their local environment, and especially to gradual geographical changes in climate across continents. Such adaptation is often expressed in the phenotype as a measurable change in size, colour, or some pdf trait.

    The gradation of form along a climatic gradient is called a cline Huxley Clines result from local populations developing tolerances to local conditions, including climate, through the process of natural selection see Saloman Commonly observed clines download pigmentation, body size, and so on have generated a book of biogeographical rules Box 2. Morphological clines may evolve very swiftly. Fifty years later it had already developed geographical variation in size and colour.

    Today it is book along the central Californian coast and southeast Mexico, and is largest on the Mexican Plateau, the Rocky Mountains, and the northern Great Plains. The clines in house bikgeography that have biogekgraphy in North America resemble the clines found in Europe Johnston and Selander The American robin Turdus migratorius displays similar geographical variation in size and shape to the house sparrow Aldrich and James : it is small in the southeastern USA and along the central Californian coast, and large downloaad the Rocky Mountains and associated high plains.

    The European wild rabbit Oryctolagus cuniculusintroduced in eastern Australia a little over a century ago, already displays clinal variation in skeletal morphology. Disjunct geographical races evolve where a population is discontinuous, comprising a set of island-like, spatially separate subpopulations. For boigeography, fineflower gilia Gilia leptantha lives in openings of montane pine forests book southern California.

    Biogeographh forests occur at middle and high elevations on biogeography ranges separated by many miles of unforested lowlands. In consequence, the plant has a disjunct geographical distribution and four disjunct geographical races Grant Or, to put it another way, birds and mammals tend to have darker feathers and fur in areas of higher humidity. This is recognized as a valid generalization about clines of melanism.

    A credible explanation downloax it nook that animals in warmer, more humid regions require more pigmentation to protect them from the light. Given that colour variation shows a concordance of pattern in birds that have vastly different competitors, diets, histories, and levels of gene flow, some common physiological adaptation seems likely. It applies biogegoraphy a wide range of birds and mammals.

    Bergmann believed many species conform to the rule because big animals have a thermal advantage over small ones in cold climates: as an object increases in size, its surface area becomes relatively smaller increasing by the square than its volume increasing by the cube. In central Europe, the larger mammals, including the red deer Cervus elaphusroe deer Capreolus capreolusbrown bear Ursus arctosfox Vulpes vulpeswolf Canis lupusand wild boar Sus scrofaincrease in size towards the northeast and decrease in size towards the southwest.

    In Biogsography, larger tigers Bok tigris tend to occur at higher latitudes. Also, many widespread Eurasian and North American bird species are largest in the highlands of the semi-arid tropics Iran, the Atlas Mountains, and the Mexican Highlandsand not in bioteography coldest part of their range. Lindsey This is borne out by Frances C. She found that wing length, a good surrogate of body size, increased in size northwards and westwards from Florida in the following species: the hairy woodpecker Dendrocopos villosusdowny woodpecker D.

    In the downy woodpecker, female white-breasted nuthatches, and female blue jays, relatively longer-winged birds tended to extend southwards into the interior highlands of Arkansas, and relatively shorterwinged birds to extend northwards into other river valleys. Pdf subtle relations between download size variation and topographic features indicated that the link between the two phenomena might involve precise adaptations to very minor climatic gradients.

    The variation in wing length in these biogeography species correlated most highly with those variables, hiogeography as wet-bulb temperature, which register the combined effects of temperature and humidity. This suggested that size variation depends on moisture levels as well as temperature. Downlozd reasoned that a relationship with wet-bulb temperature and with absolute humidity in ecologically different species strongly suggests that a common physiological adaptation is involved.

    Climate tends to be cooler, down,oad therefore drier, at high altitudes and latitudes. This accounts for the fact that many clines of increasing size parallel increasing altitude and latitude.

    Dec 01,  · Biogeography 5e. Release on | by Mark V Lomolino. Biogeography, first published in , is one of the most comprehensive text and general reference books in the natural sciences. Author: Mark V Lomolino. This section contains free e-books and guides on BioGeography, some of the resources in this section can be viewed online and some of them can be downloaded. Pure and Applied Biogeography This book, gives you a very interesting report and overview about the frontiers of such parts of recent biogeographical research, which plays important roles. 1 Biogeography: the nature of the subject, its history and its applications 1 Introduction 1 An introduction to plants, animals and other organisms 3 A history of biogeography 6 Ecology and biogeography 14 Applications of biogeography 15 Last frontiers for human exploration 20 Structure of the book 21 References 22Missing: download.

    Additionally, size tends to increase in arid regions irrespective of altitude and latitude, and widespread species tend to be largest in areas that are high, cool, and dry. Minimum summer temperatures in Israel rose by an average of 0. Allen found that protruding parts in wolves, foxes, hares, and wild cats are shorter in book regions.

    Like large body-size, short protruding parts help to reduce the surface area and so conserve heat in a cold climate. The jackrabbit subgenus Macrotolaguswhich lives in the southwestern USA, has book one third its body biogeogrwphy in the common jackrabbit Lagus campestriswhich ranges from Kansas to Canada, the ears are the same length as the head.

    Proposed by R. Dale Guthrie and Valerius Geistbook basis of this rule is that animals in areas of high seasonal food abundance can achieve a greater proportion of their potential book growth doqnload therefore develop bigger bodies. Differentiation into ecological races provides a third kind of intraspecies variation pattern. Many forms of ecological race include altitudinal races download montane species, host races in insects, and seasonal races downloae organisms with demarcated breeding systems.

    There is biogeography threshold at which microevolution evolution through adaptation within species becomes download evolution of species and higher taxa. Evolutionary biologists argue over the effectiveness of each type of speciation e. Losos and Glor First, the original population extends its range into new and unoccupied territory. The model includes cases where species extend their range by traversing an existing barrier, as when birds cross the sea dwonload colonize an island.

    Downlpad isolated for long enough, the two daughter populations will probably evolve into different bioveography. Mayr recognized three vownload a d b c e Figure 2. Mayr argued that the founding population would carry but a small sample of the alleles present in the parent population, and the colony would have to squeeze though a genetic bottleneck; he called this the founder effect.

    However, from the s onwards, it pdf apparent that the bottleneck might downliad be as tight as originally supposed, even with just a few founding intervals Pdf Some 10 to founding colonists may carry a substantial portion of the download present in the parent population. Even a single gravid female colonist, providing she is heterozygous at 10—15 per cent of her gene loci and providing an equally heterozygous biogeogrraphy largely of different alleles fertilized her, could carry a considerable amount of genetic variability.

    Admittedly, a newly founded colony will initially be more homozygous and less polymorphic than the parent population. If the colony should survive, gene mutation should restore the level of polymorphism, probably with new alleles with new allele frequencies. These species are the terminal dpf of a chain of Larus subspecies encircling the north temperate region.

    Members of the chain change pdf but the end members occur sympatrically in northwest Europe without hybridization. Vicariance events biogeography dispersal-cum-founder events may drive allopatric speciation Figure 2. Two species of North American pines illustrate vicariance speciation. Five subspecies occur on Isabela downlowd the rest occur on different islands. Once populations are isolated and become differentiated, they may then stay isolated and never come into contact again.

    If contact is reestablished, perhaps because the barrier disappears, then three things may happen: biogeography the populations may not interbreed, or fail to produce fertile offspring, reproductive isolation is complete, and speciation has occurred. This happened with the kaka and kea in New Zealand. Reinforcement is the process that selects within-population matings, and isolating mechanisms are traits that evolve to augment reproductive isolation. Peripatric speciation This is a subset of allopatric speciation.

    Peripatric speciation occurs in populations on the edge perimeter of a species range that become isolated and evolve divergently to create new species. A small founding population is often involved. An excellent example of this is the paradise kingfishers Tanysiptera of New Guinea Mayr Change between subspecies is gradual but the two end members live sympatrically in northwest Europe. Vicariance event Dispersal-cum-founder event Parapatric speciation Parapatric abutting speciation is the outcome of divergent evolution in two populations living geographically next to each other.

    The divergence occurs because local adaptations create genetic gradients or clines. A true hybrid zone may develop, which in some cases, once reproductive isolation is effective, will disappear to leave two adjacent species. An example is the main species of the house mouse in Europe Hunt and Selander A zone of hybridization separates the light-bellied eastern house mouse Mus musculus of eastern Europe and the Figure 2.

    Source: Adapted from Brown and Lomolino Figure 2. Source: Adapted from distribution maps in Mitchell-Jones et al. Sympatric speciation Sympatric speciation occurs within a single geographical area and the new species overlap — there is no spatial separation of the parent population.

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    Separate genotypes evolve and persist downloa in contact with each other. Once deemed rather uncommon, new studies booo that parapatric and sympatric speciation may be a potent process of evolution e. Via Several processes appear to contribute to sympatric speciation p. Disruptive selection favours extreme phenotypes and eliminates intermediate ones.

    Once established, natural selection encourages reproductive isolation through habitat book or positive assertive mating different phenotypes choose to mate with their biogeograpyh kind. Habitat selection in insects may have favoured sympatric speciation and account for much of blogeography large diversity of that group.

    Competitive selection, a variant of disruptive selection, favours phenotypes within a species that avoid intense competition and clears out intermediate types. The giant blue iris Iris giganticaerulea grows in damp biogeography, while its close relative, the copper iris I. Downlozd two species hybridize, but the hybrids are not as successful in growing on either the dry or very wet sites as the pure forms and usually perish.

    Stasipatric speciation Stasipatric speciation occurs within a species range owing to chromosomal changes. Chromosomal changes occur through: 1 a change biogeography chromosome numbers, or 2 a rearrangement of genetic material on a chromosome an inversion or a transferral of some genetic material to another chromosome a translocation. Polyploidy doubles or more the normal chromosome component, and polyploids are often larger and more productive than their progenitors.

    Polyploidy is rare in animals but appears to be a major source of sympatric speciation in plants: 43 per cent book dicotyledon species and 58 per cent of monocotyledon species are polyploids. Stasipatric speciation seems to have occurred in some western house mouse M. In Europe, the normal karyotype for the species contains 20 sets of chromosomes. At first, these were classed as a new species and designated M. Later, specimens from other alpine areas of Switzerland and Italy bopk well as from northern Africa and South America also had non-standard karyotypes.

    Surprisingly, all the populations showed no morphological or pf differences other than differences in their karyotypes and all belonged to M. Pdf the species are adapted to a subterranean ecotype: they are little cylinders with short limbs and no external tail, ears, or eyes. Their size varies according to heat load, presumably so that there is only a small risk of overheating under different climates: large individuals live in the Golan Heights; smaller ones in the northern Negev.

    The mole rats show several adaptations at the physiological level. Basal metabolic rates decrease progressively towards the desert. This bioeography water expenditure and the chances of overheating. More generally, the combined physiological variation in basal metabolic rates, non-shivering heat generation, body-temperature regulation, and heart and respiratory rates, appears to be adaptive at both the mesoclimatic and microclimatic levels, and both between and within species, so contributing to the optimal use of energy.

    Ecologically, territory size correlates negatively, and population numbers correlate positively, with productivity and resource availability. Lineages and clades Several download pertain to the study of species in the past Figure 2. A lineage is single line of descent. One speaks of the human lineage and the reptilian lineage. Extinction is the termination of a lineage and marks the end of the line — a lineage that failed to survive to the present.

    Extinction is the eventual fate of all species, as discussed later in this chapter. In the fossil record, speciation is the branching of lineages. In other pdf, it marks the point where a single line of descent splits into two lines that diverge from their common ancestor. It occurs book a part of a population becomes ;df isolated from the remaining populations of the established species by any of the mechanisms mentioned in the previous section.

    It is well nigh impossible download reconstruct the isolating mechanisms involved in fossil populations, although evidence may sometimes exist for geographical isolation. Fossil assemblages traced through pff reveal clades. A clade is a cluster of lineages produced by repeated branching speciation from a dowwnload lineage. The branching process that generates clades is cladogenesis. The clade Elephantinae comprises two extinct genera — Primelephas and Mammuthus — and two living genera — Elephas modern Asian elephants and Loxodonta modern African elephants.

    This supports fossil Figure 2. Evolution The fossil record permits the inference of evolutionary changes in organisms. Evolution that generates new species to create a clade or a group of clades is cladogenesis or phylogenetic evolution. Willi Henninga German entomologist, laid down its basic principles. He contended that biogeography shared derived characters synapomorphies betray a close common ancestry, and shared primitive characters symplesiomorphiesinherited from a remote common ancestor, are irrelevant or misleading when seeking phylogenetic relationships.

    In addition, he recognized characters unique to any one group autapomorphies. Biogoegraphy illustrate these ideas, consider Figure 2. The vertical bars show synapomorphies. For instance, bimanual locomotion is a derived character shared by the woolly bbook, woolly spider monkey, and spider monkey. The three shades of circles show autapomorphies, that is, characters unique to a group. Nocturnality is an autapomorphy of the owl monkey, and tool use an autapomorphy of the capuchin.

    Hennig set his ideas in an evolutionary framework — his branching diagrams are evolutionary trees with an implicit time dimension and fownload forks marking the splitting of ancestral species. The diagram of the New World monkey relationships Figure 2. However, it is possible to look at branching downliad in a more general way that has no evolutionary connotations. They can be seen biogeograhy cladograms with no timescale and the nodes simply imply shared downllad synapomorphies.

    The pdf between evolutionary trees and cladograms downnload appear minor, but they are hugely important Patterson A cladogram is a summary the pattern of character distributions among taxa, in which the nodes are shared characters and the lines are immaterial, the relationships being expressible as a Venn diagram Figure 2. Phylogenetic evolution contrasts biogeography phyletic evolution anagenesis, chronospeciationin which an established species slowly changes into another species within the same lineage.

    The new species produced in this way go by a variety of names: chronospecies, palaeospecies, and evolutionary species. The recognition of chronospecies is arbitrary and subjective: it is assumed that, in Europe, Mammuthus primigenius evolved by phyletic biogeograaphy from M. When a chronospecies changes into boigeography new form, pseudoextinction sometimes bigoeography phyletic extinction occurs.

    Thus M. Occasionally, a key innovation is thrown up that permits species to exploit a lifestyle novel to that taxon dowlnoad, sometimes, new to any form of life. Such key innovations may help to trigger adaptive radiation see p. Innovations book be brand new or they can be exaptations. Book are characters acquired from ancestors that download co-opted for a new use. An example is the blue-tailed gliding lizard Holaspis guentheri from tropical Africa that has a flattened head, biogeogrwphy allows bjogeography to hunt and hide in narrow crevices biogepgraphy bark.

    A big debate surrounds the question of evolutionary patterns shown by clades and groups of clades. Two extreme cases arise: 1 all evolution is concentrated in speciation the branching of lineages and 2 all evolution takes place within lineages Figure 2. The second cases give rise to the gradualistic model of evolution, blok most evolution ppdf as phyletic change and rapid divergent speciation playing a minor role. All species share characters A to F. This is the fate of nearly all newly formed species.

    Species are similar to each other after pdf speciation event, but are likely to diverge when exposed to different environments with different selective pressures. The biogeographical equivalent of the biogeography exclusion principle p. A striking example of this is sibling or cryptic species that are genetically distinct but very close in ecology and morphology.

    Sibling species commonly display abutting, but non-overlapping parapatric geographical ranges, numerous examples coming from animals and plants. Several species of pocket gophers of download genera Thomomys and Geomys have ranges that come into contact in North America but do not overlap. Where species ranges do overlap, then there are normally big differences in resource use achieved through slight differences in niches seen in form, physiology, and behaviour that evolve through character displacement p.

    Download full-text PDF Download full-text PDF Read full-text. This book had its origin when, about five years ago, an ecologist (MacArthur) and a taxonomist and Estimated Reading Time: 6 mins. This section contains free e-books and guides on BioGeography, some of the resources in this section can be viewed online and some of them can be downloaded. Pure and Applied Biogeography This book, gives you a very interesting report and overview about the frontiers of such parts of recent biogeographical research, which plays important roles. Download Biogeography Lectures Download free online book chm pdf.

    It is one the most important processes bridging ecology and evolution. It occurs when a single ancestor species diverges, through recurring speciation, to create many kinds of descendant species that become or remain sympatric. These species tend to diverge to avoid interspecific competition. Even when allopatric species are generated, some divergence still occurs as the allopatric species adapt to different environments.

    Examples of adaptive radiation are legion. A single ancestor, possibly the blue-black grassquit Figure 2. Allopatric speciation resulting from repeated episodes of colonization and divergence within the island group created 5 genera and 13 species. The beaks of the different species match their diet — seed eaters, insect eaters, and a bud eater. The Hawaiian Islands have fostered adaptive radiations. It is now known that many more species formed part of the radiation in the recent past, with 29—33 recorded in historical times and 14 as subfossil remains.

    The radiation produced seed eaters, insect eaters, download nectar eaters, all with appropriately biogeography beaks. The Hawaiian silversword alliance, described as the most remarkable example of adaptive radiation in plants, displays an extreme and rapid divergence of form biogeography physiology. The common ancestor of the silversword alliance, which split from Californian tarweeds about 13—15 million years ago, arrived in Hawaii some 4—6 million years ago.

    It has produced a wide range of plants that spans almost the complete gamut of environmental conditions found on Hawaii, with an altitudinal range from 75 to 3, m. Lemurs in Madagascar are the product of an adaptive radiation in primates that began with the arrival of a common ancestor some 50 million years ago Tattersall Sportive lemurs are nocturnal and move mainly by jumps. Mouse lemurs Microcebus are small up to 60 grun like rodents, and eat insects as well as fruits.

    The indri and sifakas Propithecus are large animals up to 1 m long. Archaeolemur lived on the ground and was about the size of a female baboon. The kg Megaladapis was arboreal with a niche similar to that of a koala. At 60 pdf, Palaeopropithecus was a sloth-like tree-dweller. Non-radiative and non-adaptive radiation Not all adaptations are radiative and not all are adaptive.

    This Hawaiian tree species is very diverse and has a wide range of forms. But it is ascribed to a single species despite such a rich variety of forms. Non-adaptive radiation occurs where radiation is associated with no clear niche pdf. It may occur when radiations have occurred allopatrically in fragmented book. All species occupy roughly the same or only a narrow range of habitats, but rarely do any two Albinaria download live in the same place. Parallel evolution book parallelism refers to changes in two closely related stocks that differ in minor ways and that both go through a similar series of evolutionary changes.

    It is similar to convergence, except that in convergence the original species are from very different stocks, unlike the stocks in parallel evolution, which are similar to start with. Marsupials and placental mammals are a case in point, though sometimes thought of as a case of convergent evolution. A local extinction or extirpation is the loss of a species or other taxon from a particular place, but other parts of the gene pool survive elsewhere.

    The American bison Bison bison is now extinct over much of its former range, but survives in a few areas p. A global extinction is the total loss of a particular gene pool. When the last dodo died, its gene pool was lost forever. An example is the global extinction of the sabre-toothed cats, one of the main branches of the cat family. Mass extinctions stand out in the fossil record as times when the extinction rate runs far higher than the background or normal extinction rate p.

    Some The fossil record suggests that mammal genera last about 10 million years, with primate genera enduring only 5 million years. Individual species survive even less time, something around 1 to 2 million years for complex animals. Examples are the horseshoe crab Limulus spp. Coelacanths have persisted nearly unchanged for 70 million years.

    Biogeography PDF Notes in English

    Periods of rapid climatic change, sustained volcanic activity, and asteroid and comet impacts seem to cause mass extinctions. Normal pd depend on many interrelated factors that fall into three groups — biotic, evolutionary, and abiotic. Biotic factors Most biotic factors of extinction are densitydependent factors. This means their action depends upon population size or density.

    The larger the population, the more effective is the factor. Density-dependent factors are chiefly biotic in origin. They include factors related to biotic properties of individuals and populations body size, niche size, range size, population size, generation time, and dispersal ability and factors related to biogeography with other species competition, disease, parasitism, predation.

    Biotic properties Body size, niche size, and range size all affect the probability of extinction. As a rule, large animals are more likely to become extinct than small animals. Smaller animals can probably better adapt to small-scale habitats when the environment changes. Specialist species with narrow niches are more vulnerable dowbload extinction than are generalists with wide niches. Small populations are more prone to extinction through chance events, such as droughts, than are large populations.

    In other words, there is safety in numbers. Tropical birds living in patches of Amazon forest book that populations of 50 or more are about 5 times less likely to go extinct locally than are populations biogeography 5 or fewer. Species with rapid generation times stand more chance of dodging extinction.

    Good dispersers are better placed to escape pdf that poor dispersers, as are species with better opportunities for dispersal. In addition, a species with a large gene pool may be better able to adapt to environmental changes than species with a small gene pool. This is because restricted range species are more vulnerable to chance events, such as a severe winter or drought. In a widespread species, severe events may cause local extinctions but are not likely to cause a global extinction.

    This generalization is borne out by defaunation experiments on red mangrove Rhizophora mangle islands downooad the Florida Keys, USA, where the insects, spiders, mites, and other terrestrial animals were exterminated with methyl bromide gas see Simberloff and Wilson Analysis of the data revealed that the probability of invertebrate extinctions decreased with the number of islands occupied Hanski It should be pointed out that a widespread distribution is not a guarantee of extinction avoidance.

    The passenger pigeon Ectopistes migratorius and the American chestnut Castanea dentata were abundant with widespread distributions in downloae North America in the nineteenth century, but suffered range collapse and extinction in the case of the passenger pigeon p. The bison B. Widespread species also appear to be less at risk than restricted species to mass extinctions. For instance, extinction rates of marine bivalves and gastropods that lived along the Atlantic and Gulf coastal plains of North America in the late Cretaceous period increased with species range Jablonski Biotic interactions Competition can be a potent force of extinction.

    Species have to evolve to outwit their competitors, and a species that cannot evolve swiftly enough is in peril of becoming extinct. Virulent pathogens, such as viruses, may evolve or arrive from elsewhere to destroy species. The fungus Phiostoma ulmi, which is carried mainly by the Dutch elm beetle Scolytus multistriatuscauses Dutch elm disease.

    Starting in the Netherlands, Dutch elm disease spread download continental Europe and into the USA during the s to s, ravaging the elm populations. After a decline in Europe but not in the USAit re-emerged as an even more virulent form described as a new species — Ophiostoma novoulmi download the mids to affect Britain and most of Europe. Predators at the top of food chains are more susceptible to a loss of resources than are bok lower pdf. Island mammal, book, and reptile populations are especially vulnerable to all sorts of competitive and predatory introduced species Bjogeography 2.

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    Since and up to the late sspecies of birds have become extinct. Of this total, Table 2. In pef cases, numerous species of sea birds survive only on outlying islets where introduced species have failed to reach. The story for mammals and reptiles is similar. Evolutionary biogeography Several evolutionary changes may, by chance, lead to some species being more prone to extinction than others. A species bioteography evolve on an island and not possess the dispersal mechanisms to escape if the island should be destroyed or should experience bool change.

    Some species may become overspecialized through adaptation and fall into evolutionary traps. Biogeography interesting download of this idea is that species alive today must be descendants of non-specialized species. Behavioural, physiological, and booi complexity, as varieties of specialization, also appear to render a species more prone to extinction. Simple species — marine bivalves for example — survive for book 10 million years, whereas complex mammals survive pdf 3 million years or less.

    Abiotic factors Abiotic factors of extinction are usually densityindependent factors, which means that they act uniformly on populations of any size. Densityindependent factors tend to be physical in origin — climatic change, sea-level change, flooding, asteroid and comet impacts, and other catastrophic events. Take the example of the song doqnload Turdus philomelos.

    It was absent from Shetland in the nineteenth century but established a colony on the island inbreeding near trees, which were scarce in Shetland, the largest group being planted in By the s, about pdf of breeding pairs inhabited the island. The severe winter of —7 reduced the population to some three or four pairs from then until Abiotic factors are usually implicated in mass extinctions.

    However, several researchers stress the potential role biogeogra;hy diseases as drivers of mass extinctions. Lethal pathogens pdc by the dogs, rats, and other animals associated with migrating humans may have caused the Pleistocene epoch mass extinctions MacPhee and Marx p. Similarly, it is possible that the terminal Cretaceous extinction event might have resulted from changes of palaeogeography, in which land connections created by falling sea-levels allowed massive migrations from one landmass to another, leading boo, biotic stress in the form of predation and disease: The shallow oceans drained off and a series of extinctions ran through the saltwater world.

    A monumental immigration of Asian dinosaurs streamed into North America, while an equally grand migration of North American fauna moved into Asia. In every region touched by this global intermixture, disasters large and small would occur. A foreign predator might suddenly thrive unchecked, slaughtering virtually defenseless prey as its population multiplied beyond anything possible in its home bkogeography.

    But then the predator might suddenly disappear, victim of a disease for which download had no immunity. As species intermixed from all corners of the globe, the result could only have been global biogeographical chaos. Changes in gene pools fownload by mutation, genetic drift, gene flow, and natural selection drive the formation of new species and subspecies.

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    In adapting to local environments, some species produce clines — geographical variations in particular characteristics. The mechanisms of speciation are complex and open to considerable debate. Biologists recognize several types of speciation — allopatric, peripatric, parapatric, sympatric, and stasipatric. Looked at over geological timescales, speciation is the branching of lineages lines of descentwith extinctions marking the end of lineages.

    Clades are clusters of lineages formed by repeated branching or speciation events, a process called cladogenesis or phylogenetic evolution. Speciation within a lineage is phyletic evolution and produces chronospecies. Convergent evolution and parallel evolution arise from species experiencing the same environmental pressures in geographically separate regions coming to look alike. Extinction occurs locally and regionally, when it is an extirpation, and globally. Global extinction is the ultimate fate of all species.

    Extinction occurs because of biotic, evolutionary, and abiotic factors. Biotic factors include body size, range size, population size, dispersal ability, competition, disease, and predation. Evolutionary factors are a question of luck — some species during their evolution happen to acquire a characteristic that leaves them in evolutionary blind alleys or traps. Abiotic factors include climatic change, sea-level change, asteroid impacts, and other catastrophic events.

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    New York: Oxford University Press. A collection of essays on the theme of generating new species and diversity. Not easy but rewarding. Lawton, J. Oxford: Oxford University Press. Schilthuizen, M. An engaging and informative introduction to the subject. Ideal for beginners. Schluter, D. Looks at the ecological causes of adaptive radiation.

    Stearns, S. Individuals roam into new areas, either as adults or as eggs and seeds, and establish colonies. All organisms can, to varying degrees, move from their birthplaces to new locations. The adults of higher plants and some aquatic animals are sessile rooted to one spotbut are capable of roving large distances in their early stages of development. Organisms disperse when they move to, and attempt to colonize, areas outside their existing pdf. Some species travel huge distances on an annual basis to avoid harsh conditions, to feed, or to mate.

    Such seasonal migrations do not involve the colonization of new areas outside the species range and do not count as dispersal, and nor do episodic irruptions of populations, such as the irruptions of the desert locust Schistocera gregaria that swarms northwards from its central African core. The stage in the life cycle of an organism that does the dispersing is a propagule. In plants and fungi, a propagule is the structure that serves to reproduce the species — seed, spore, stem, or root cutting.

    In animals, a propagule is the smallest number of individuals of a species able to colonize a new download. Depending upon the biological and behavioural needs of the species, it is a fertilized egg, a mated female, a male and a female, or a group of individuals. Dispersal Organisms disperse. The jump takes less time than the life-span of the individual involved. An insect carried over sea by the wind is an example. It takes place over many generations. Species that expand their ranges little by little are said to be diffusing.

    Another example is the nine-banded armadillo Dasypus novemcintus that has spread, and is still spreading, from Mexico to the southeastern USA Figure 3. By the time population arrives in a new region, it will differ from the ancestral population in the source area. South American members of the family Figure 3. Its maximum possible range is constrained by rainfall and temperature. They are all descended from now extinct North American ancestors that underwent a secular migration during the Pliocene epoch over the then newly created Isthmus of Panama.

    Physical agencies wind, water, landmasses or biological agencies other organisms, including humans bring about passive dispersal. These various modes of transport are given technical names — anemochore for wind dispersal, thalassochore for sea dispersal, hydrochore for water dispersal, anemohydrochore for a book of wind and water dispersal, and biochore for hitching a ride on other organisms. Anemochores include many plant species biogeography have seeds designed for wind transport.

    Some animals are anemochores: young black widow spiders Latrodectus mactans spin long strands of web that catch the wind and carry the small spiders many kilometres. Many other insects are borne aloft and carried great distance by the wind. Ancestors of many of the native spiders, mites, and insects on the Hawaiian Islands made the air trip from Asia, Australia, and North America, which are 3, to 4, kilometres away. Hydrochores include the adults, larvae, and eggs of many aquatic organisms. The coconut palm Cocos nucifera is a striking thalassochore.

    The thick husk and shell of the coconut keep the seed afloat and safeguard it from sea water as it drifts for long periods in ocean currents. When a coconut beaches on a tropical island, it may germinate and grow into a mature tree. The tiny plumed seeds of the aspen are anemohydrochores, being biogeography of dispersal by wind or water. Anemochory is very useful for plants living in floodplains and on islands. Biochores include zoochores dispersed by animals and anthropochores dispersed by humans.

    Zoochores travel as seeds on fur, feathers, or clothing pdfas is the case with cleavers Galium aparinethe fruits of which are spherical with hooked bristles and adhere to fur and clothing. Alternatively, they are deliberately moved and book as seeds by a herbivore, as in the case of acorns collected and secreted by a squirrel. Or else they may pass as seeds though their digestive system of a herbivore that eats their fruits download. A sheep was specially tamed to stand still while it was groomed for seeds.

    The seeds were a mixture of hooked, bristled, and smooth forms. Figure 3.

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    Notice that sea-dispersed or thalassochore species — biogeography of which live along strandlines — are rapid colonizers. The anemochores comprise three ecological groups. The very early colonists are mostly ferns, grasses, and composites members of the Compositaewhich are common in early pioneer habitats. These second-phase colonists require conditions that download more humid. Numerically, most of them are epiphytes. The third group consists of seven primarily wind-dispersed trees.

    Animal-dispersed zoochore organisms are the slowest to colonize. Birds and bats mainly carry them. Animal-dispersed zoochores Wind-dispersed anemochores Good and bad dispersers Dispersal abilities vary enormously. Lizards, tortoises, and rodents come next, followed by small carnivores. Not all large mammals are necessarily inept at crossing water. It pvf to check their swimming proficiency before drawing too many biogeographical conclusions ibogeography their distributions.

    Johnsonit was widely assumed that elephants must have walked pdf these islands from mainland areas, taking advantage of former land bridges though vicariance events are also a possibility. Biogeograaphy elephants could bioveography swum to the islands, new explanations for the colonization of the dowhload are required. Tigers, too, have a surprisingly high degree of mobility in water. They can swim for up to 29 km across rivers or 15 km across the sea Kitchener Supertramps are ace dispersers.

    They move with book across ocean water and reproduce very rapidly, setting up thriving colonies. The collation periods are indicated on the horizontal axis. Human-introduced species are excluded. Source: Adapted bkogeography Bush and Whittaker Diamond Long was devegetated and defaunated about two centuries ago by a volcanic explosion. The diversity of biogeograpy species is now far higher than would be expected Figure 3.

    Of the 43 species present on the island, 9 were responsible for the high density. These were the supertramps. They specialize in occupying islands too small to maintain stable, long-lasting populations, or islands devastated by catastrophic disturbance — volcanic eruptions, tsunamis, or hurricanes. The distances are extremes and probably not typical of the groups. The dandelion occurs on all continents save Antarctica. Dispersal routes The ease bilgeography rate at which organisms disperse depend on two things: the topography and climate of the terrain over which they are moving and the wanderlust of a particular species.

    Topography and climate may impose constraints upon dispersing organisms. Obviously, organisms disperse more easily over hospitable terrain than over inhospitable terrain.


    Abundance was measured by the daily capture rate book nets. Long Island is exceptional because population density is abnormally high for an island of its size. This high biogeovraphy is due largely to the presence of supertramp species. An example is a land bridge combined with a climatic barrier that bars the passage of some migrants.

    In biology, download winners are those few lucky individuals that manage to survive a chance journey by water or by air biogeography succeed in colonizing places far from their homeland. Williams Faunas are free to move in both directions. These are akin to stable pdf bridges, but there are two differences. First, biogeograpny gaps periodically interrupt access in both directions.

    Second, faunas on one or both sides may suffer extinction, owing to the loss of area during times of separation. These downloaf fragments biogeograpphy lithospheric plates carrying entire faunas with them from one source area to another see p. These are a fairly permanent or temporary series of islands separated by moderate to small water gaps. They are similar to stepping-stone islands, but there are fewer arrivals arriving at much longer time intervals.

    They are not true sweepstakes routes because the pdg of arriving depends on species characteristics — some species have a much better chance of arriving than others do. Given enough time, probably no barrier is insurmountable: One morning [in Glacier Park], dark streaks were observed extending downward at various angles from saddles or gaps in the mountains to the east of us.

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    Later in the day, these streaks appeared to be much longer and at the biogeography end of each there could be discerned a dark speck. As they reached lower levels not so far distant, they proved to be porcupines. From every little gap there poured forth a dozen or twenty, or in one case actually fifty five, of these animals, wallowing down to the timberline on the west side.

    Hundreds of porcupines were crossing the main range of the Rockies. The chief problem in detecting dispersal in action is that detailed species distributions are scarce. Most instances of organisms moving to new areas probably pass unnoticed — is a new sighting an individual that has moved in from elsewhere, or is it an individual that was born in the area but not seen before?

    Despite these problems, there are several amazing cases of present-day dispersal resulting from human introductions. An example of a deliberate introduction is the coypu Myocastor coypusbrought from Download America to Britain in the s pdf its fur nutria. Numerous escapes occurred and it established itself in two areas: at a sewage farm near Slough, where a colony lived from toand in East Anglia, with a centre in the Norfolk Broads Lever A concerted trapping programme seems to have eradicated the coypu from Britain Gosling and Baker An accidental introduction was the establishment of the ladybird Chilocorus nigritus in several Pacific islands, northeast Brazil, west Africa, and Oman after shipment from other areas Book Successful, half-successful, and failed introductions Not all introductions survive; some gain a foothold but progress little further; others go rampant and swiftly colonize large tracts of what is to them uncharted book. A dispersing organism will fail if it cannot colonize a new location.

    Dispersal ability does not necessarily equate with colonizing ability. Some hundred species of birds from Asia and Europe arrive in North America every biogeography but do not set up permanent populations. Environmental factors that may hinder colonization include adverse physical conditions and unfavourable biotic conditions. Tropical plants and animals that disperse to high latitudes are unlikely to survive the colder climate.

    Of the biotic factors that stand to impede colonization, download ranks high. A colonist is unlikely to oust a superior competitor. Failed dispersers include several species that were unsuccessfully taken to New Zealand — bandicoots, kangaroos, racoons, squirrels, bharals, gnus, camels, and zebras. Amphibians and reptiles in Ireland appear to be reluctant dispersers.

    Just four species of amphibians and reptiles live in Ireland, compared with twelve on the British mainland. The species are the natterjack toad Bufo calamitathe common newt Triturus vulgaristhe common or viviparous lizard Lacerta viviparaand the common frog Rana temporaria. So, why have only three species of amphibians and reptiles colonized Ireland? One explanation is that other newts and toads did establish bridgeheads, but they died out because they were unable to sustain large enough colonies for successful invasion.

    The present distribution of the natterjack toad in Ireland, which is restricted to a small part of Kerry and shows no signs of spreading, lends this view some pdf. Its spread in North America was an indubitable ecological explosion — within 60 years it had colonized the entire USA and much of Canada. For example, in20 pairs of starlings vanished after their release in Portland, Oregon. Then in April80 birds were released in Central Park, New York, and in March the following year a further 80 birds were released.

    From that staging post, it expanded its range very rapidly, colonizing some 7, km2 in 50 years Figure 3. The speed of dispersal was due to the irregular migrations and wanderings of non-breeding 1- and 2year-old starlings. Adult birds normally use the same breeding ground year after year and do not colonize new areas. The roaming young birds frequented faraway places.

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