Unit 8

acquired trait

A trait that an organism gains during its lifetime, not coded for in DNA, and cannot be passed on.

adaptation

A trait an organism has that increases its chance to survive and/or reproduce.

adaptive radiation

Speciation in which a common ancestor rapidly diverges into many different species.

allele frequency

The relative abundance of an allele in a population, expressed as a decimal, percentage, or fraction.

analogous structures

Features of different species that are similar in function but not in structure, based on the environment, not common ancestry.

behavioral adaptation

Something an organism does in order to survive and/or reproduce, such as hibernation or mating dances.

behavioral isolation

When two species that could reproduce do not due to different behaviors, exemplified by the Western and Eastern Meadowlark mating calls.

biological resistance

An evolutionary process where an organism becomes resistant to a chemical designed to kill it, such as bacteria to antibiotics.

cladogram

A diagram that shows relationships between species based on observable physical characteristics.

coevolution

When two species evolve in direct relation to each other, like a hummingbird and the flower it pollinates.

comparative anatomy

Examining the internal structure of organisms that share a recent common ancestor as evidence of evolution.

comparative biochemistry

Examining the protein or DNA sequences of organisms that share a recent common ancestor as evidence of evolution.

comparative embryology

Examining embryonic development of organisms that share a recent common ancestor as evidence of evolution.

convergent evolution

When distantly related organisms appear similar due to similar environmental pressures.

divergent evolution

When species with a common ancestor become more different over time.

evolution

Change in the allele frequency of a population over time.

fitness

The reproductive success of an organism measured by the number of offspring produced.

fossil record

The history of life through preserved remains, providing evidence of evolution.

gene flow

Movement of individuals between separated populations, reducing genetic differences.

gene pool

All of the alleles present in a population.

genetic diversity

The total number of genetic characteristics in the genetic makeup of a species, with higher diversity indicating stability.

genetic drift

A random event that decreases population size and often reduces genetic diversity.

geographic isolation

When a population is separated physically, which can lead to the formation of new species.

homologous structures

Features with the same structure but different functions found in different organisms, indicating a common ancestor.

inherited trait

A trait that an organism is born with, coded in its DNA.

mutation

A random change in an organism’s DNA.

natural selection

A mechanism of evolution by which organisms better adapted to their environment tend to survive and reproduce.

phylogenetic tree

A branching diagram illustrating relationships between species based on common ancestry.

physiological adaptation

A chemical produced by an organism to aid survival, like spider venom.

reproductive isolation

When two populations, once a single species, no longer reproduce, leading to speciation.

speciation

The evolution of a new species.

species

A group of organisms that can interbreed and produce fertile offspring.

structural adaptation

Physical features of an organism that aid its survival, such as a giraffe's long neck.

temporal isolation

When two groups breed at different times, preventing interbreeding.

variation

Multiple versions of a phenotype within a population.

vestigial structures

Structures present in an organism that serve no current function and indicate divergent evolution.