Term
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Definition
| a change over time in the genetic composition of a population of organisms |
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Definition
| preserved remains of ancient organisms |
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Definition
| dating of fossils based on the fact that Earth’s magnetic poles move and occasionally reverse themselves. Because both sedimentary and volcanic rock rocks preserve a record of Earth’s magnetic field at the time they were formed, paleomagnetism helps determine the ages of those rocks. |
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Definition
| time during which early life evolved amid stupendous physical changes on Earth |
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Definition
| the movement of plates and the continents they contain |
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Definition
| solid slabs of rock containing all land on Earth |
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Definition
| the molten, fluid material under the plates |
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Definition
| the extermination of a large proportion of the species living at a certain time |
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Definition
| dramatic increases in the diversity of major groups of organisms |
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Definition
| all living species of all kinds at a certain time |
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| scientist who studies fossils |
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Term
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Definition
543-490mya, at the beginning of the Paleozoic era
the O2 concentration in the atmosphere approached its current level and the continental plates came together to form several land masses |
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Term
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Definition
| the rapid diversification of life during the cambrian period |
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Term
| Five Periods of the Paleozoic Era |
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Definition
Ordovician
Silurian
Devonian
Carboniferous
Permian |
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Term
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Definition
490-443mya
the continents, which were located primarily in the Southern Hemisphere, were still devoid of multicellular plants. Evolutionary radiation of marine organisms was spectacular during early Ordovician, esp. among animals that filter small prey from the water |
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Definition
443-417mya
the northern continents coalesced, but the general positions of the continents did not change much. Marine life rebounded from the mass extinction at the end of the Ordovician. Animals able to swim and feed above the ocean bottom appeared. the first known tracheophytes (plants with true vascular tissue) appeared late in the Silurian period. First terrestrial arthropods (scorpions, millipedes) appeared late in Silurian. |
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Term
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Definition
417-354mya
rates of evolutionary change accelerated in many groups of organisms. Both the northern and southern land masses slowly moved northward. Great evolutionary radiations of corals and shelled squid-like cephalopods. Jawed fishes replaced jawless ones, heavy armor for less rigid armor.All current major groups of fishes were present by the end of the period. Mosses and ferns became common toward the end of the Devonian era, up to the size of current trees. Deep roots accelerated rock weathering. Ancestors of gymnosperms (first plants to produce seeds) appeared in fossil records of this time. An extinction of 75% of all marine species marks the end of the era, and scientists are unsure as to the reason for this (meteor collisions might have caused this) |
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Term
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Definition
| large glaciers and extensive swamp forests grew. Forests dominated by giant tree ferns and horsetails, formed the coal we now mine for energy. Diversity of terrestrial animals increased greatly (snails, scorpions, centipedes, and insects were abundant and diverse). Insects evolved wings. Amphibians became larger and better adapted to terrestrial existence. “Meadows” of plants on the sea floors formed. |
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Term
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Definition
| Continents coalesced into a supercontinent, Pangaea. Volcanic eruptions resulted in blocking of the sunlight and cooling of the Earth, forming the largest glaciers in Earth’s history. Fossils contain representatives of the most modern groups of insects. Reptiles greatly outnumbered amphibians. Because of meteor crashes, the ocean waters became reduced in oxygen and increased in toxic concentrations of CO2 and hydrogen sulfide, poisoning the air. Caused the extinction of about 96% of Earth’s species of animals |
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Term
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Definition
| 248mya; Pangaea slowly separated into individual continents, the climate warms, glaciers melted, and oceans rose and reflooded continental shelves, causing huge shallow inland seas. Earth’s biota became increasingly provincialized, influencing the geography of life today. Divided into 3 periods: Triassic, Jurassic, and Cretaceous. |
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Term
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Definition
| distinctive terrestrial floras and faunas evolved on each continent |
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Definition
248-206mya
Pangaea began to break apart. Many invertebrate lineages became more diverse. Conifers and seed ferns became the dominant trees. First frogs and turtles appeared. Radiation of reptiles began, giving rise to crocodilians, dinosaurs, and birds. End is marked by mass extinction that eliminated about 65% of species on Earth, possibly caused by a large meteor crash |
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Term
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Definition
206-144mya
Two large continents formed: Laurasia in the north, and Gondwanna in the south. Diversification of many lineages proceeded. Several groups of mammals first appeared. |
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Definition
144-65mya
sea levels were high, and Earth was warm and humid. Life proliferated in the ocean and on land. Marine invertebrates increased in number and species. Dinosaurs continued to diversify. Another meteorite-caused mass extinction, esp. of insects, planktonic organisms, and bottom-dwelling invertebrates |
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Definition
64mya
the positions of the continents resembled those of today, but Australia was still connected to Antarctica, and the Atlantic Ocean was much narrower. Characterized by an extensive radiation of mammals, but other groups were also undergoing important changes. Flowering plants diversified extensively and came to dominate world forests in warm regions. Divided into two periods, Tertiary and Quaternary. |
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Term
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Definition
65-1.8mya
Australia begins its northern drift. A hot, humid time, during which vegetation belts shifted latitudinally. In the middle of the Tertiary, Earth’s climate became considerably drier and cooler. Invertebrate faunas reselmbed those of today. Most rapid evolutionary changes occurred in vertebrates. Rodents, marsupials, primates, and hoofed animals appeared for the first time in N. America. |
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Term
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Definition
1.8mya to present
subdivided into two epochs, Pleistocene and Holocene. |
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Term
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Definition
| time of drastic cooling and climatic fluctuations. Massive glaciers spread across the continents, and animal and plant populations shifted toward the equator. Last of these glaciers retreated from temperate latitudes less than 15,000 years ago, marking the beginning of the Holocene epoch. Time of hominid evolution and radiation, resulting in modern humans |
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Definition
| also known as the Recent. Followed the Pleistocene Epoch in Quaternary Period of Cenozoic Era |
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Term
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Definition
| the study of how different organisms carry out their lives |
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Term
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Definition
| slight variations among individuals significantly affect the chance that a given individual will survive and reproduce |
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Definition
| the differential contribution of offspring to the next generation by various genetic types belonging to the same population, proposed by Darwin. Allele frequencies in a population change in a way that adapts individuals to the environments that influenced their success |
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Definition
| a group of individuals of a single species that live in a particular geographic area at the same time. Individuals do not evolve, populations do |
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Definition
| the processes by which adaptive traits are acquired—that is, the evolutionary mechanisms that produce them. Also, the traits that enhance the survival and reproductive success of their bearers |
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Definition
| the application of Mendel’s laws to entire populations of organisms |
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Definition
| the physical expression of organisms’ genes |
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Definition
| the features of a phenotype (eye color) |
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Term
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Definition
| the specific form of a character |
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Term
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Definition
| A characteristic of an organism that is at least partly determined by its genes |
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Definition
| the genetic constitution that governs a character. A population evolves when individuals with different genotypes survive or reproduce at different rates |
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Term
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Definition
| different forms of a gene |
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Term
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Definition
| the sum of all copies of alleles found in the population |
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Term
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Definition
| a locally interbreeding group within a geographic population |
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Term
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Definition
| the relative proportions of alleles in a population |
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Term
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Definition
| the frequencies of different alleles at each locus and the frequencies of different genotypes in a Mendelian population |
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Term
| Hardy-Weinberg Equilibrium |
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Definition
applies to sexually reproducing organisms; the allele frequency at a given locus in a sexually reproducing population that is not being acted on by agents of evolution. Several conditions must be met:
a.Mating is random
b.Population size is very large
c.There is no migration between populations
d.There is no mutation
e.Natural selection does not affect the alleles under consideration |
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Term
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Definition
| the exchange of genes between different species (an extreme case referred to as hybridization) or between different populations of the same species caused by migration following breeding |
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Term
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Definition
| the random loss of individuals and the alleles they possess |
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Term
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Definition
| occasional periods in the history of a population when only a small number of individuals survive, reducing variation in the gene pool |
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Term
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Definition
| when a few pioneering individuals colonize a new region, reducing the variation in the gene pool of the species in that area. |
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Term
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Definition
| the reproductive contribution of a phenotype to subsequent generations relative to the contributions of other phenotypes. The fitness of a phenotype is determined by the average rates of survival and reproduction of individuals with that phenotype. |
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Term
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Definition
| preserves the average characteristics of a population by favoring average individuals; reduces variation, but does not change the mean |
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Term
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Definition
| changes the characteristics of a population by favoring individuals that vary in one direction from the mean of the population |
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Term
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Definition
| changes the characteristics of a population by favoring individuals that vary in both directions from the mean of the population |
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Definition
| Darwin’s explanation for the evolution of apparently useless but conspicuous traits in males of many species, such as bright colors, long tails, horns, antlers, and elaborate courtship displays. He hypothesized that these traits either improved the ability of their bearers to compete for access to members of the other sex (intrasexual selection) or made their bearers more attractive to members of the other sex (intersexual selection). |
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Term
| Sexually Dimorphic Species |
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Definition
| species where the males appear quite different from the females. Males of these species are significantly larger than females and often bear large weapons needed to defend a male’s multiple mates against other males of the species |
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Term
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Definition
| an allele that does not affect the fitness of an organism |
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Term
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Definition
| the coexistence within a population, at frequencies greater than mutations can produce, of two or more alleles at a locus. |
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Term
| Frequency-dependent Selection |
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Definition
| the process by which a polymorphism may be maintained, when the fitness of a genotype or phenotype varies within its frequency relative to that of other genotypes or phenotypes in a population. |
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Term
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Definition
| the acquisition of new traits by learning them from other individuals in a population |
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Term
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Definition
| the basic lower unit of classification, consisting of a population or series of populations closely related and similar organisms. The more narrowly defined “biological species” consists of individuals capable of interbreeding freely with each other but not with members of other species |
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Definition
| the process of splitting one population into two populations that are reproductively isolated from one another, which thereafter evolve as distinct lineages |
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Definition
| speciation that results when a population is divided by a physical barrier, also known as geographic speciation |
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Term
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Definition
| a partition in a gene pool resulting from factors besides physical separation |
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Term
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Definition
| the production within an individual of duplicate sets of chromosomes |
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Term
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Definition
| polyploidy from chromosome duplication in a single species |
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Term
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Definition
| the combining of the chromosomes of two different species |
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Term
| Prezygotic Reproductive Barriers |
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Definition
| processes that operate before fertilization, outside of reproduction |
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Term
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Definition
Prezygotic Reproductive Barriers
individuals of different species may select different places in the environment in which to live. As a result, they ay never come into contact during their respective mating periods; that is, they are reproductively isolated by location |
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Term
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Definition
Prezygotic Reproductive Barriers
many organisms have mating periods that are as short as a few hours or days. If the mating periods of two species do not overlap, they will be reproductively isolated by time.
11. Mechanical isolation: differences in the sizes and shapes of reproductive organs may prevent the union of gametes from different species |
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Term
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Definition
Prezygotic Reproductive Barriers
sperm of one species may not attach to the eggs of another species because the eggs do not release the appropriate attractive chemicals, or the sperm may be unable to penetrate the egg because the two gametes are chemically incompatible |
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Term
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Definition
Prezygotic Reproductive Barriers
individuals of a species may reject, or fail to recognize, individuals of other species as mating partners |
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Term
| Postzygotic Reproductive Barriers |
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Definition
| processes that prevent interbreeding, because of reproductive incompatibilities |
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Term
| Hybrid Zygote Abnormality |
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Definition
Postzygotic Reproductive Barriers
hybrid zygotes may fail to mature normally, either dying during development or developing such severe abnormalities that they cannot mate as adults |
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Term
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Definition
Postzygotic Reproductive Barriers
hybrids may mature normally, but be infertile when they attempt to reproduce. For example, the offspring of matings between horses and donkeys—mules—are strong, but sterile; they produce no descendents |
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Term
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Definition
Postzygotic Reproductive Barriers
hybrid offspring may simply survive less well than offspring resulting from matings within population |
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Term
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Definition
| the strengthening of prezygotic barriers |
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Term
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Definition
| narrow zone where two populations interbreed, producing hybrid individuals |
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Term
| Variation of Speciation Rates |
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Definition
a number of factors are known to influence speciation rates:
a.species richness: the larger the number of species in a lineage, the larger the number of opportunities for new species to form
b.dispersal rates: individuals of species with poor dispersal abilities are unlikely to establish new populations by dispersing across barriers. Even narrow barriers are effective in dividing species whose members are highly sedentary
c.ecological specialization: populations of species restricted to habitat types that are patchy in distribution are more likely to diverge than are populations that occupy relatively continuous habitats
d.population bottlenecks: the changes in gene pools that often occur when a population passes through a bottleneck may result in new adaptations
e.type of pollination: speciation rates in plants are correlated with pollination mode.
f.Sexual selection: animals with complex behavior are likely to form new species at a high rate because they make sophisticated discriminations among potential mating partners
g.Environmental changes: oscillations of climates may fragment populations of species that live in formerly continuous habitats |
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Term
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Definition
| the proliferation of a large number of daughter species |
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Term
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Definition
| a species that is found nowhere else |
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Definition
| the study of the diversity of organisms |
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Definition
| a subdivision of systematics, it is the theory and practice of classifying organisms |
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Definition
| a hypothesis proposed by a systematist that describes the history of descent of a group of organisms from their common ancestor |
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Definition
| a way of portraying the lineage of an organism |
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Term
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Definition
| traits inherited from a common ancestor |
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Term
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Definition
| any features shared by two or more species that have been inherited from a common ancestor |
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Definition
| a trait that differs from its ancestral form |
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Definition
| the evolution of similar features independently in unrelated taxa from different ancestral structures |
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Definition
| the reappearance of the ancestral state of a trait in a lineage in which that trait had acquired a derived state |
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Term
| Homoplastic Traits (Homoplasies) |
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Definition
| traits that are similar for some reason other than inheritance from a common ancestor |
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Term
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Definition
| the lineage of interest; traits found only within the ingroup are likely to be derived traits |
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Term
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Definition
| the lineage that is related to the ingroup, but which branched off from the ingroup before its base on the evolutionary tree |
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Term
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Definition
| the sizes and shapes of body parts |
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Definition
| theory that states that one should prefer the simplest hypothesis that is capable of explaining the observed data. |
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Term
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Definition
| a group of closely related species |
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Definition
| any group of organisms that is treated as a unit in a biological classification system |
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Definition
| the taxon above the genus; the names of animal families ends in the suffix “-idae”, Hominidae contains humans and our recent fossil relatives, as well as chimps and gorillas |
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Definition
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Term
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Definition
| in taxonomy, a high-level category just beneath kingdom and above the class; a group of related, similar classes |
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Definition
| the phyla of plants, fungi, and animals |
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Definition
a.k.a. clade
group that contains all the descendents of a particular ancestor and no other organisms |
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Definition
| a group containing some members that do not share the same common ancestor |
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Definition
| a group that contains some, but not all, of the descendents of a particular ancestor |
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Term
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Definition
| certain Paraphyletic groups that have undergone rapid evolutionary change and diversification and evolved distinctive characters |
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