AP Biology Unit 7 Terms

Charles Darwin

He was a British nationalist that proposed the theory of biological evolution by natural selection.

Traits

(Characteristics) are heritable = inherited/passed down from parents to offspring.

Genes

DNA code(s) that make up an organism's traits, characteristics, innate behaviors, etc

Individual Organism

One organism.

Population

Many organisms of the same species living together in a given space.

Community

Different species living together in a given space.

Ecosystem

Communities + nonliving factors such as rain, sun, etc.

Biome

Many similar ecosystems.

Biosphere

The whole system including the atmosphere.

Natural Selection

Ability of an organism to survive and reproduce based on their adaptation to an environment.

Fitness

Ability to survive and reproduce (including attracting a mate), NOT how big/strong.

Overpopulation

Populations produce more offspring than an environment can support.

Carrying Capacity

Maximum amount of organisms an ecosystem can support.

Genetic Variation

Individuals in a population have different traits.

Mutations

Any change in DNA.

Meiosis

A special type of cell division that creates gametes (sex cells).

Sexual Reproduction

The production of new organisms by the combination of genetic information of two individuals of different sexes.

Gene Flow

Movement of traits between populations.

Selective Pressure

Any cause that makes an organisms better or worse at surviving.

Density-Dependent Pressures

Amount of individuals in the population matters. (PANDA)

Density-Independent Pressures

Amount of individuals in the population does NOT matter. (PAW)

Adaptation

Good variations are passed down and increase fitness.

Batesian Mimicry

Specie looks like a harmful species to avoid being eaten.

Mullerian Mimicry

Venomous species looks like another venomous species.

Aggressive Mimicry

Predator looks like prey to capture the actual prey.

Cryptic Coloration

Camouflage = organism blends in with its environment.

Aposematic coloration

Organisms “signal” that they are poisonous through bright coloration.

Uniform Dispersion

Organisms are equally spaced out.

Random Dispersion

Organisms are randomly spaced out.

Clumped Dispersion

Organisms are grouped together.

Microbiology

Biology on a small scale. (i.e. cells)

Macrobiology

Larger biology (i.e. natural selection and ecology)

Nucleus

“Brain” of the cell; has all of the genes of an organism. (contains chromosomes = genes)

Cell

Has lots of different organelles.

Allele

ONE gene(or trait) represented by a letter.

Genotype

Genetic makeup of an organism. (which 2 alleles the organism has)

Phenotype

The physical trait of the organism from the genotype and behavioral traits.

Dominant Allele/Gene

Dominant always wins and shows in phenotype (capitalized letter).

Recessive Allele/Gene

Only shows in phenotype when there is no dominant allele (lowercase letter).

Homozygous

BOTH letters in a genotype are the SAME.

Heterozygous

BOTH letters are DIFFERENT.

Stabilizing Selection

Intermediate (middle) phenotypes are more fit than extremes.

Directional Selection

One extreme phenotype is more fit than the others.

Disruptive Selection

Both extremes are more fit.

Predation Selection

Environment acts on prey and predator.

Physiological Selection

Acts on body functions and structures.

Coevolution

2+ species evolve together.

Evolution

A gradual change in genes of a population over time because favored traits survive and reproduce (natural selection).

Emigration

Exit to a new location.

Immigration

Into a new location.

Sexual Dimorphism

Two different forms of the same species (usually between male and females).

Genetic Drift

Change in allele frequency from generation to generation due to chance events. (occurs by chance)

Artificial Selection

Humans select for desirable traits in agricultural products or animals, rather than leaving the species to evolve and change gradually without human interference, like in natural selection.

Frequency

% or decimal of how often something occurs (# / TOTAL #)

Allele Frequency

# of dominant or recessive alleles / total alleles.

p

Frequency of dominant allele.

p²

Frequency of homozygous dominant.

q

Frequency of recessive allele.

q²

Frequency of homozygous recessive.

2pq

Frequency of heterozygous.

Gene Pool

Total gene copies in a population.

Locus

Physical site of where a gene is held on a chromosome.

Biogeography

Geographical distribution of organisms.

Pangea

All land masses were once all together.

Fossil

Remains or traces of past organisms

Fossil Record

Gives a visual of evolutionary change over time.

Sedimentary Rock

Contain fossils = strata = gives a “timeline”

Transitional Fossils

Show evolutionary links between groups of organisms.

Comparative Morphology

Analysis of the structures of living and extinct organisms.

Homology

Characteristics in related species that have similarities even if the functions differ.

Embryonic Homology

Many species have similar embryonic development.

Vestigial Structures

Structures that are conserved even though they no longer have a use. (ex./ tailbone and appendix in humans)

Molecular homology

Many species share similar DNA and amino acid sequences.

Analogous Structures

Similar features due to adapting to the environment NOT because of ancestors.

Convergent Evolution

Come together.

Homologous Structures

Similar features due to a common ancestor.

Divergent Evolution

Separate into two.

Comparative Embryology

Similar embryological development in closely related species.

Phylogenetic Trees/Cladograms

Diagrams that show evolutionary relationship of different species w/ a common ancestor.

Outgroup

The lineage that is least closely related to the remainder of the organisms in the phylogenetic tree or cladogram.

Shared Derived Traits

Traits that indicate common ancestry.

Biological Species Concept

Organisms that can interbreed (mate) with one another to produce viable, fertile offspring are the same species.

Speciation

Creation of a new species due to inability to interbreed.

Allopatric Speciation

Physical separation by a geographical barrier causes divergent evolution.

Sympatric Speciation

Divergent evolution NOT due to physical separation.

Prezygotic Barriers

Barriers that stop organisms from interbreeding BEFORE fertilization (sperm meets egg).

Postzygotic Barriers

Barriers that stop organisms from creating viable offspring AFTER fertiliation.

Habitat Isolation

Two+ species live in different habitats.

Mechanical Isolation

Two+ species reproductive structures cannot fit together.

Behavioral Isolation

Two+ species have different courtship behaviors or mate preferences.

Temporal Isolation

Two+ species reproduce at different times.

Gametic Isolation

Two+ species produce eggs/sperms that cannot combine.

Hybrid Breakdown

Offspring generations breakdown/progressively become unhealthy.

Reduced Hybrid Viability

Hybrid cannot survive or is unhealthy.

Reduced Hybrid Fertility

Hybrid cannot produce offspring.

Extinction

Disappearance of a species.

Deletarious

Traits reduce fitness.

Adaptive

Traits increase fitness.