Unit 01 Ch 18 Evolution & The Origin of Species

Question 1

adaptation

Answer 1

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

Question 2

adaptive radiation

Answer 2

speciation when one species radiates to form several other species

e.g. Island archipelagos like the Hawaiian Islands provide an ideal context for adaptive radiation events because water surrounds each island which leads to geographical isolation for many organisms. Over time, the varied demands of their new lifestyles lead to multiple speciation events originating from a single species

Question 3

allopatric speciation

Answer 3

(other + homeland) speciation that occurs via geographic separation

involves geographic separation of populations from a parent species and

Question 4

allopolyploid

Answer 4

polyploidy formed between two related, but separate species

Question 5

aneuploidy

Answer 5

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

Question 6

autopolyploid

Answer 6

a condition in which an organism has more than two sets of chromosomes that come from the same species

Question 7

behavioral isolation

Answer 7

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

Question 8

convergent evolution

Answer 8

process by which groups of organisms independently evolve to similar forms (e.g. in bird and bats evolved from different structures)

Question 9

dispersal

Answer 9

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

Question 10

divergent evolution

Answer 10

process by which groups of organisms evolve in diverse directions from a common point (e.g. the reproduction organs of flowering plants which share same basic anatomy but look different)

Question 11

gametic barrier

Answer 11

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

Question 12

gradual speciation model

Answer 12

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

Question 13

habitat isolation

Answer 13

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

Question 14

homologous structures

Answer 14

parallel structures in diverse organisms that have a common ancestor

Question 15

hybrid

Answer 15

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

Question 16

hybrid zone

Answer 16

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

Question 17

natural selection

Answer 17

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

Question 18

postzygotic barrier

Answer 18

reproductive isolation mechanism that occurs after zygote formation (includes organisms that do not survive the embryonic stage and those born sterile)

Question 19

prezygotic barrier

Answer 19

reproductive isolation mechanism that occurs before zygote formation (includes barriers that prevent fertilization when organisms attempt reproduction)

Question 20

punctuated equilibrium

Answer 20

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

Question 21

reinforcement

Answer 21

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

Question 22

reproductive isolation

Answer 22

a set of processes that prevent different species from breeding and producing fertile offspring

Question 23

speciation

Answer 23

formation of a new species (the formation of two species from one original species)

For speciation to occur, two new populations must form from one original population and they must evolve in such a way that it becomes impossible for individuals from the two new populations to interbreed.

Question 24

species

Answer 24

group of populations that interbreed and produce fertile offspring

Question 25

sympatric speciation

Answer 25

(sym- = “same”; -patric = “homeland”) speciation that occurs in the same geographic space

involves speciation occurring within a parent species remaining in one location.

Question 26

temporal isolation

Answer 26

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

Question 27

variation

Answer 27

genetic differences among individuals in a population

Question 28

vestigial structure

Answer 28

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

Question 29

vicariance

Answer 29

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

Question 30

hybrid inviability

Answer 30

When fertilization takes place and a zygote forms, postzygotic barriers can prevent reproduction. Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages. We call this hybrid inviability because the hybrid organisms simply are not viable.

Question 31

hybrid sterility

Answer 31

another postzygotic situation, reproduction leads to hybrid birth and growth that is sterile. Therefore, the organisms are unable to reproduce offspring of their own.