Zoology Chapter 1: Evolutionary Biology

Vocabulary-style flashcards covering key terms and their definitions from the lecture notes on evolution, phylogeny, and natural selection.

Biology

The study of life.

Zoology

The scientific study of animals, their traits, and how and why they are the way they are; a part of biology.

Phylogeny

A branching genealogical tree that depicts the history of animal life, showing propagation from a common ancestor through branching lineages.

Phylogenetic tree

A diagram depicting the history of animal life where branches represent evolutionary lineages and each branching event reflects the splitting of an ancestral species to form new species.

Proximate (causes)

Immediate explanations for biological processes at multiple levels (molecular, cellular, organismal, population) guiding metabolic, physiological, and behavioral functions.

Ultimate (causes)

Evolutionary processes that produced biological systems and properties over time.

Experimental method

A method to test proximate causes involving predicting a system’s response to a treatment, applying the treatment, and comparing results with predictions, using controls to reduce bias.

Comparative method

A method to test ultimate causality by comparing characteristics across species to identify patterns and reconstruct phylogeny.

Variation

Differences in characters between individuals in a population; in genetics, the occurrence of different alleles of a gene.

Character

Variations in characters (character states) that can be phenotypic, behavioral, cellular, biochemical, or chromosomal.

Character state

Variations in characters.

Heredity

Variations must be heritable; offspring tend to resemble their parents.

Gene

The unit of heredity; a DNA segment that often codes for a protein.

Reproductive success

Having more surviving offspring than others due to one's character states; central to natural selection.

Perpetual change

The theory that life has a long history of ongoing change with hereditary continuity across generations.

Common descent

All forms of life originate from a common ancestor via branching lineages, forming a phylogenetic tree.

Multiplication of species

Darwin’s idea that evolution produces new species by splitting and transforming older ones.

Gradualism

The idea that large differences arise from many small changes over long times, not from sudden genetic changes.

Natural selection

Differential survival and reproduction leading to accumulation of favorable traits over time (adaptation).

Overproduction

Each species tends to produce more individuals than can reach maturity.

Adaptation

A trait that evolved by natural selection for a particular biological role.

Physical (adaptation)

Physical traits such as fur, feathers, wings, fins, camouflage, and mimicry.

Physiological (adaptation)

Physiological traits such as thermoregulation and toxins.

Sensory (adaptation)

Sensory traits like vision, smell, hearing, echolocation.

Behavioral (adaptation)

Behaviors related to survival, feeding, reproduction, mating, parental care, sociality, etc.

Fossil

Preserved remains or traces of past organisms (bones, amber, imprints, burrows, feces).

Fossil record

A chronological progression of life forms; biased due to selective preservation.

Trend

Directional changes in features or diversity within a group.

Transitional fossil

Fossils showing intermediary stages between major animal groups.

Homologous structures

Similar structures with different functions due to common ancestry.

Analogous structures

Functionally similar but nonhomologous structures; e.g., wings of bats and birds.

Vestigial structures

Reduced or nonfunctional remnants of features that were functional in ancestors.

DNA

The chemical name for the long molecule in cells that reveals genetic similarities and differences between species.

Molecular clock

Mutations occur at a roughly constant rate in DNA, so more time since common ancestry equals more differences.

Endemic species

Species found only in a specific location.

Convergent evolution

Similar traits arising independently in different lineages due to similar environments.

Divergent evolution

Related species evolving different traits due to differing environments or niches.

Embryology

Study of animal development; developmental similarities in early embryos suggest common ancestry.

Artificial selection

Human-directed breeding of animals for desired traits.

Neo-Darwinism

Darwinian theory revised by Weismann, incorporating Mendelian genetics and the chromosomal theory of inheritance.

Nucleotide

The building blocks that make up DNA.

Allele

Different versions of the same gene.

Mutation

DNA copying errors; the ultimate source of new alleles and variation.

Genetic drift

Random fluctuations in allele frequencies across generations, stronger in small populations.

Population bottleneck

A sharp reduction in population size followed by recovery, reducing genetic variation by chance.

Migration

Movement of individuals from one population to another before mating.

Gene flow

Movement of genes between populations; zero gene flow can lead to divergent evolution.

Stabilizing selection

Selection that favors average trait values and disfavors extremes.

Disruptive selection

Selection that favors extreme trait values over the average.

Directional selection

Selection that favors one extreme trait value.

Sexual selection

Natural selection for traits that improve mating success, even if they hinder survival.

Kin selection

Preference for helping closely related individuals; related to inclusive fitness.

Inclusive fitness

Fitness derived from helping relatives reproduce; includes effects of an allele on relatives.

Mass extinction

Episodic events causing the extinction of many taxa nearly simultaneously.

Species selection

Differential survival and reproduction of species based on lineage-level variation.

Speciation

Process by which one species splits into two or more species; requires geographic or reproductive isolation.

Adaptive radiation

Rapid production of many ecologically diverse species from a common ancestor.

Allopatric speciation

Speciation due to reproductive barriers evolving between geographically separated populations.

Sympatric speciation

Species formation without geographic isolation.

Reproductive barrier

Biological factors preventing interbreeding between species.

Prezygotic barrier

Barriers acting before fertilization to prevent mating or fertilization.

Temporal isolation

Prezygotic barrier where species breed at different times.

Habitat isolation

Prezygotic barrier where species occupy different habitats.

Behavioral isolation

Prezygotic barrier based on mating behaviors.

Mechanical isolation

Prezygotic barrier with incompatible reproductive structures.

Gametic isolation

Prezygotic barrier where sperm and egg cannot fuse.

Postzygotic barrier

Barriers that act after fertilization, affecting hybrid viability or reproduction.

Reduced hybrid viability

Hybrids fail to develop or reach maturity.

Reduced hybrid fertility

Hybrids are sterile (e.g., mules).

Hybrid breakdown

Hybrids are viable and fertile, but offspring are inviable or sterile.

Punctuated equilibrium

A model where phenotypic evolution happens in brief bursts of branching speciation, separated by long periods of stasis.