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Key terms for exam (Part III of course) This is a list of all the key terms included for the exam from Fall 2008. This includes not only definitions but facts that can be used in the definition section. From "speciation" to "paleogene and neogene period

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Jon Houseman

KEY TERMS PART III Speciation Allopatric speciation The divergence of populations into different species by physical isolation of populations in different geographic areas. There are two kinds: vicariance and dispersal. Characteristics of a colonizing population are likely to be different from original species due to founder effects. *65 - 66 Allopolyploidy The state of having more than two full sets of chromosomes (polyploidy) due to hybridization between two species. If two arent able to combine, they may duplicate separate genes and will make diploid gametes. Only plants are able to do this example is Tragopogon specis introduced to North America hybridized and formed offspring that became teatraploid and formed new species. *70 Autopolypoloidy The state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number. Ex: maidenhead ferns, mistake in meiosis in ancestor and created species of tetraploid ferns. They become genetically isolated with incapacity to mate with anyone but themselves. *69 Behavioural isolation This is an example of prezygotic isolation. Ways that males compete for females separate species. Certain rituals ensure there are no mixing, other birds will not react to rituals. Ex: fireflies, they signal each other in a specific way, only the same species respond. *61 Biological species The biological species concept is the definition of a species as a population or group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed in nature to produce viable, fertile offspring but cannot produce viable, fertile hybrid offspring with members of other species. This speciation caused by prezygotic and postzygotic isolation. Disadvantages: we cannot use criterion on fossils or those that reproduce asexually. *54 Disruptive selection A pattern of natural selection that favours extreme phenotypes at both ends of the range of phenotypic variation. Maintains overall genetic variation in a population. This is the only way speciation can occur. An example is the size of birds (big birds can eat big seeds, small birds have small seeds). Disruptive selection occurs on intermediates of two different species or subspecies that are not viable. *68 Gametic isolation A form of prezygotic isolation where two species are separated because they have different gametes. In Cambrian, a lot of the species released sperm, proteins on the surface of the cells recognize sperm of their own species *63 Habitat isolation A form of prezygotic isolation where species cannot mate due to different habitats. Ex: insects in field, it will spend life on plant, and even though on next plant they will never meet each other. *60 Hybrid sterility A form of postzygotic isolation. This occurs when the hybrid between two offspring make no alleles produced by hybrid. Ex: donkeys and horse makes mule, its viable but it cannot breed (sterile). *64 Hybrid viability One form of postzygotic isolation. If two species do mate, the hybrid will not be fit as the others. Selective pressures prefer two extremes, causes disruptive selection. Ex: salamanders diverged in California, traits fit environment but the intermediate has only a duller version the traits needed to survive. *64 Hybrid zone A geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring. Ex: hybrid zones for birds. *72 Hybridization The formation of a hybrid, an intermediate of product when two species mate. Hybrids may either be viable and exist in population, sometimes they are superior to original and sometimes they are unviable. *72 Mechanical isolation A form of prezygotic isolation. This occurs when the genitalia do not interconnect in a suitable way to transfer gametes. The master of this is the insect, they have very unique grooves, only sperm can transfer if they fit. *62 Morphospecies The morphological species concept is the definition of a species as a population or group of populations that have measurably different anatomical features from other groups. Biologists will use traits to distinguish species, logic is that features are different when isolated from gene flow. Advantage can be used with bacteria and fossils. Disadvantage: subjective *57. Phylogenetic species The definition of a species as the smallest monophyletic group in phylogenetic trees. Two main advantages: 1) can be applied to any population, 2) logical because populations are distinct enough to be monophyletic. Disadvantage: may recognize too many species, no well-developed phylogenies for all species. *56 Polyploidy The state of having more than two full sets of chromosomes. This occurs with an error in meiosis and mitosis that results in doubling of chromosome number. Only plants can produce viable polyploidy species. Two general mechanisms for polyploidy individuals involved in speciation: autopolyploid and allopolyploid. *69 - 70 Population A group of individuals of the same species living in the same geographic area at the same time. Defines a gene pool Postzygotic isolation mechanisms Reproductive isolation resulting from mechanisms that operate after mating of individuals of two different species occurs. The most common mechanisms are the death of hybrid embryos or reduced fitness of hybrids. Hybrids may either be not viable or sterile. *64 Prezygotic isolation mechanisms Reproductive isolation resulting from any one of several mechanisms that prevent individuals of two different species from mating. There are a variety of kinds: habitat, temporal, behaviour, mechanical and gametic. *60 - 63 Reinforcement If hybrid offspring has low fitness, natural selection favours the evolution of traits that prevent interbreeding between the populations. Example: appears to be common in fruit fly species that occupy the same geographic areas. *71 Reproductive isolation This causes speciation. The inability of two populations to interbreed because they are geographically isolated, or isolated from each other by differences of behaviour, mating time (or in plants maturation times of male and female sex organs),or genital morphology. This is a phase o the development of new species. *60 Speciation The evolution of two or more distinct species form a single ancestral species. This occurs when natural selection or evolution occurs with allele frequency changes. They become reproductively isolated. *54 Subspecies A population that has distinctive trait sand some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species. Ex: dogs, a subspecies of wolves. Species can still reproduce. *59 Sympatric speciation The divergence of populations living within the same geographic area into different species as the result of their genetic (not physical) isolation. This contradicts the idea that lack of gene flow will result in speciation. Ex: soapberry fruitflies. *66 Temporal isolation A form of reproductive isolation, that is prezygotic isolation. This isolation is caused because the two species are not reproductively active at the same time, some breed in spring while others breed n fall. They separate when they are reproductively active. *60 Tetraploid An organism that has four sets of chromosomes, usually what happens when two diploid gametes merge together. Only plants are able to survive in this way. There is a species of ferns that are tetraploid. *69 Triploid An organism that has three sets of chromosomes, the offspring of a diploid gamete and haploid gamete. This is not viable because during mitosis, when it splits each cell wont have the same number of chromosomes, why animals cannot be polyploidy. *69 Vicariance The physical splitting of a population into smaller, isolated populations by a geographic barrier. This often causes speciation, an example of allopatric speciation. An example is the marsupial mammals. Causes difference in the two gene pools. *65 - 66 Organizing the Living World Adaptive radiation Rapid evolutionary diversification within one lineage, producing numerous descendant species with a wide range of adaptive forms. Each species becomes adapted to a geological niche. Ex: massive number of changing after end of dinosaur era *18 - 19 Advanced characters Opposite to primitive, of a more evolutionary origin. Synonymous with synapomorphy or derive trait. Analogous Structures that are similar in function but not in structure and developmental and evolutionary original. Ex: wings of insects and birds. * 7 - 9 Apomorphy In cladistic phylogenetics, a novel character evolved from a pre-existing character. The original and the derived character form a homologous pair termed an evolutionary transformation series. Ex: triploblasts. *21 Artificial taxonomy First created by Plato and his students Aristotle and Theophrastus. They wrote down all of the folk taxonomies, compiling lists of living things, Aristotle his animals and Theophrastus the plants. They were passed onto generations as reference tool around world. Lists were based on detailed descriptions of objects being classified rather than unique names. *4 Character convergence In evolution, condition in which two newly evolved species interact in such a way that one or both converges in one or more traits towards the other. Character reversal In evolution, a condition where a species character reverses to a more primitive state. Cladistics Method of classification of living organisms that makes use of lines of descent only, rather than phenotypic similarities, to deduce evolutionary relationships, and which groups of organisms strictly on the relative recency of
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