Openstax Biology - Chapter 18 - Evolution & The Origin Of Species

Front 1

adaptation

Back 1

heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment

Front 2

adaptive radiation speciation

Back 2

when one species radiates out to form several other species

Front 3

allopolyploid

Back 3

polyploidy formed between two related, but separate species

Front 4

aneuploidy

Back 4

condition of a cell having an extra chromosome or missing a chromosome for its species

Front 5

behavioral isolation

Back 5

type of reproductive isolation that occurs when a specific behavior or lack of one prevents reproduction from taking place

Front 6

convergent evolution

Back 6

process by which groups of organisms independently evolve to similar forms

Front 7

dispersal

Back 7

allopatric speciation that occurs when a few members of a species move to a new geographical area

Front 8

divergent evolution

Back 8

process by which groups of organisms evolve in diverse directions from a common point

Front 9

gametic barrier

Back 9

prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs and sperm) prevent fertilization from taking place

Front 10

gradual speciation model

Back 10

model that shows how species diverge gradually over time in small steps

Front 11

habitat isolation

Back 11

reproductive isolation resulting when populations of a species move or are moved to a new habitat, taking up residence in a place that no longer overlaps with the other populations of the same species

Front 12

homologous structures

Back 12

parallel structures in diverse organisms that have a common ancestor

Front 13

hybrid

Back 13

offspring of two closely related individuals, not of the same species

Front 14

hybrid zone

Back 14

area where two closely related species continue to interact and reproduce, forming hybrids

Front 15

natural selection

Back 15

reproduction of individuals with favorable genetic traits that survive environmental change because of those traits, leading to evolutionary change

Front 16

postzygotic barrier

Back 16

reproductive isolation mechanism that occurs after zygote formation

Front 17

prezygotic barrier

Back 17

reproductive isolation mechanism that occurs before zygote formation

Front 18

punctuated equilibrium

Back 18

model for rapid speciation that can occur when an event causes a small portion of a population to be cut off from the rest of the population

Front 19

reinforcement

Back 19

continued speciation divergence between two related species due to low fitness of hybrids between them

Front 20

reproductive isolation

Back 20

situation that occurs when a species is reproductively independent from other species; this may be brought about by behavior, location, or reproductive barriers

Front 21

speciation

Back 21

formation of a new species

Front 22

species

Back 22

group of populations that interbreed and produce fertile offspring

Front 23

sympatric speciation

Back 23

speciation that occurs in the same geographic space

Front 24

temporal isolation

Back 24

differences in breeding schedules that can act as a form of prezygotic barrier leading to reproductive isolation

Front 25

variation

Back 25

genetic differences among individuals in a population

Front 26

vestigial structure

Back 26

physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor

Front 27

vicariance

Back 27

allopatric speciation that occurs when something in the environment separates organisms of the same species into separate groups

Front 28

allopatric speciation

Back 28

speciation that occurs via geographic separation

Front 29

autopolyploid

Back 29

polyploidy formed within a single species