Chapter 3

Front 1

Adaptation

Back 1

Any heritable trait in an individual that has evolved by past natural selection to make birds with the trait more successful at survival and reproduction.

Front 2

Natural Selection

Back 2

An evolutionary process in which the higher survival and reproduction of individuals with favorable inherited traits causes those traits to increase in the population over time.

Front 3

Fitness

Back 3

The relative success of an individual -compared with other individuals in their population- in passing along their own genes to later generations.

Front 4

Heritability

Back 4

The proportion of the variation in a trait that is due to underlying genetic variation.

Front 5

Reproductive Sucess

Back 5

The number of viable offspring produced by an individual over their lifetime.

Front 6

Lek

Back 6

An aggregation of males that engage in competitive mating displays towards visiting females.

Front 7

Direct Fitness

Back 7

The fitness an individual bird gains through its own production of offspring; direct fitness is usually measured via a bird's lifetime reproductive success.

Front 8

Indirect Fitness

Back 8

The component of an individual's fitness that results not from their own reproduction, but rather by the aid they give to relatives that then enhances their relative's reproductive success.

Front 9

Total Fitness

Back 9

The sum of direct fitness via the individual's own reproduction plus their indirect fitness via their relative's reproduction. Sometimes also termed "absolute fitness."

Front 10

Hamilton's Rule

Back 10

The formula that describes when an individual should forgo its own reproduction and instead help its relative reproduce

rB>C

r - genetic relatedness of the individual and it's breeding relative

B - additional number of offspring brought about by this behavior

C - cost to helper in form of offspring not produced.

Front 11

Kin Selection

Back 11

Natural selection arising through indirect fitness, via the reproduction of relatives that are aided by an individual.

Front 12

Artificial Selection

Back 12

The evolutionary process analogous to natural selection that results when humans are the selective agent that determines which individuals are allowed to reproduce; often this occurs when humans selectively breed individuals for desirable traits.

Front 13

Sexual Selection

Back 13

A special form of natural selection that involves the differential reproductive success of individuals that arises specifically from competition over mating opportunities; this can involve direct competition with members of the same sex or competition to attract members of the opposite sex.

Front 14

Reverse Sexual Dimorphism

Back 14

A situation in which the sex that is usually smaller or less ornamented is the larger or more conspicuous sex in a particular species. (When females are the flashier sex.)

Front 15

Intersexual Selection

Back 15

A subset of sexual selection, one involving the reproductive success of individuals that depends on the actions of the opposite sex. (mate choice)

Front 16

Direct Benefits

Back 16

The tangible benefits that a mate derives directly from their partner, such as food access to a good territory, protection from predators, or a high-quality nest site.

Front 17

Courtship Feeding

Back 17

A behavior in which one member of a pair (usually the male) presents his potential partner with food during courtship or before mating. The food item is sometimes called a "nuptial gift" and this behavior is an important part of pair bonding in some species.

Front 18

Handicap Principle

Back 18

The hypothesis that females of some species have evolved mating preferences for males who display very costly and exaggerated ornaments or behaviors, since these costs ensure that only particularity high-quality males can afford these so-called handicaps. (Amotz Zahavi)

Front 19

Runaway Sexual Selection

Back 19

A hypothesis for how extremely exaggerated ornaments or behaviors might evolve, via a feedback loop that involves females choosing males with the extremes of that trait, the resulting generations of male offspring having more and more elaborate variants of the trait, and the resulting female offspring having ever stronger preference for males with the trait.

Front 20

Good Genes Benefits

Back 20

The fitness advantage that individuals (usually females) gain by selecting mates on the basis of the genetic qualities that they will pass on to their mutual offspring.

Front 21

Inbreeding

Back 21

The offspring resulting from matings between individuals who are more closely related than would be expected by chance within a population.

Front 22

Extra-pair Ferilization

Back 22

The fertilization of eggs resulting from matings between two members of a population who are not pair bonded.

Front 23

Intrasexual Selection

Back 23

A subset of sexual selection, one involving the reproductive success of individuals that depends on competition with members of the same sex. (Usually competition among males over access to females).

Front 24

Sperm Competition

Back 24

In birds, a form of intrasexual selection that arises after more than one male has copulated with the same female, and therefore the sperm of multiple males are in competition to fertilize an egg within the female's reproductive track.

Front 25

Speciation

Back 25

The evolutionary process by which one ancestor lineage splits into two or more descendant species.

Front 26

Reproductive Isolation

Back 26

A mating incompatibility that occurs when some kind of behavioral, physiological, or genetic barrier prevents successful interbreeding among individuals from two different populations even where they occur together.

Front 27

Behavioral Isolation

Back 27

A form of reproductive isolation involving incompatibilities in behavior that prevent the interbreeding of two populations. These can include behaviors involved in recognizing members of the same species, specialized courtship displays, or any other behaviors necessary for successful mating.

Front 28

Geographic Isolation

Back 28

A barrier to interbreeding between two populations that arises from them being separated in space, often with some kind of geographic barrier to movement between them.

Front 29

Habitat Isolation

Back 29

A barrier to interbreeding between two populations that arises from them being found in different habitats, even if otherwise they are in close proximity.

Front 30

Mechanical Isolation

Back 30

A barrier to interbreeding between two populations that arises from an incompatibility between the male genitalia of one species and the female genitalia of the other species.

Front 31

Dispersal

Back 31

The movement of an individual bird from one breeding site to another.

Front 32

Allopatric

Back 32

Populations that occur in separate regions with no geographic overlap.

Front 33

Refugia

Back 33

Geographic regions that remained relatively unaltered by past changes in climate or other environmental shifts, and which therefore supported populations of organisms that were lost in the surrounding regions.

Front 34

Vicariance

Back 34

The subdivision of a species' originally large distribution into smaller and separated geographic fragments via some new geographic barrier or the fragmentation of the species' originally widespread habitat.

Front 35

Vicariant Speciation

Back 35

Speciation that results over time after populations that become divided by new barriers have diverged from one another.

Front 36

Landbridge Islands

Back 36

Islands that were formerly part of the nearby mainland, and which often retain some of the birds and other organisms from that earlier period, that were created by a rise in the level of the ocean. In contrast, oceanic islands rose directly out of the sea, and all land organisms on them had to have arrived by over-water colonization.

Front 37

Supertramp Species

Back 37

A term applied to bird species that are particularly good at dispersing long distances and at colonizing newly created habitats.

Front 38

Steppingstone Dispersal

Back 38

The dispersal that proceeds by a series of colonizations, one after another, across a chain of islands or among habitat patches.

Front 39

Founder Event

Back 39

The loss of genetic variation that occurs when a new populations is established by a very small number of individuals immigrating from a much larger source population.

Front 40

Sympatric Speciation

Back 40

The speciation that occurs even when the two diverging populations breed in the same locations and therefore have the possibility of intermixing within each generation.

Front 41

Temporal (Allochronic) Speciation

Back 41

An unusual form of speciation in which the two diverging populations occur in the same location, but diverge because they reproduce at different times of the year.

Front 42

Reinforcement

Back 42

A situation in which natural selection fosters the divergence of two hybridizing populations, either by selecting against hybrid offspring directly or by favoring individuals that choose members of their own population as mates.

Front 43

Hybrid Zone

Back 43

A geographic area where two species (or distinct populations) come into contact and hybridize.

Front 44

Suture Zone

Back 44

The somewhat controversial idea that broad-scale changes in past habitats have affected many species in similar ways and thereby created locations where multiple hybrid zones overlap

Front 45

Ecotone

Back 45

A transition zone connecting two habitats and the communities of birds and other organisms that occur in them.

Front 46

Hybrid Index

Back 46

A number derived from measuring a series of traits or genes that describes the proportion of a hybrid individual's ancestors that belonged to each parental species.

Front 47

Ecological Speciation

Back 47

The evolution of reproductive isolation between populations as a result of divergent natural selection in their different locations or environments.

Front 48

Adaptive Radiation

Back 48

Evolutionary radiations that are exceptional in having quickly evolved many species from a common ancestor, in response to natural selection that causes these species to differ from one another in their use of their environment.