Evolutionary Processes and Speciation

Flashcards covering key concepts in evolutionary processes leading to speciation.

Adaptive Radiation

lots of new species arise in a short time due to vacant niches

Allopatric Speciation

Populations become geographically isolated, stops gene flow leads to speciation

Allopolyploidy

polyploidy, different species mating = hybrid

Autopolyploidy

polyploidy, chromosome sets from same species

Cline

gradual variation in the characteristics of a species over geographical range

Coevolution

When two or more species influence each other's gene pools, acting as selection pressures

Convergent Evolution

develop similar structures in unrelated species due to similar environmental selection pressures

Divergent Evolution

changes in gene pools of two or more populations, leading to new species from a common ancestor

Evolution

cumulative changes occur in heritable characteristics

Founder effect

When individuals from a larger population establish a new population

Gene Pool

total number of genes of every individual in a population

Gene Flow

movement of genes from one population of a species to another

Genetic Drift

Process, populations change over generations, random events, not selection pressures acting on phenotypes

Hybrid

offspring of parents differing in at least one characteristic, usually from different species

Instant Speciation

speciation through polyploidy

Macro-evolution

formation of completely new species

Micro-evolution

accumulation of new characteristics in a species through mutation

Mutation

Permanent change in DNA base sequence, new alleles

Natural Selection

Process, individuals have differing levels of reproductive success = change populations over generations

Nondisjunction

Failure of homologous chromosomes to separate during cell division

polyploidy

cell or organism with two or more sets of chromosomes

Population Bottleneck

event drastically reduces population size, decrease gene pool

postzygotic isolating mechanism

isolation preventing fertile offspring formation, including hybrid inviability, sterility, and breakdown.

prezygotic isolating mechanism

isolation preventing fertilisation of eggs, geographical, temporal, behavioural, mechanical, gametic mechanisms

Reproductive Isolation

inability of species to interbreed and produce fertile offspring due to reproductive barriers

Selection Pressure

environmental aspect influencing an individual's success

Speciation

Formation of new species from a common ancestor

Species

group of individuals that can interbreed, produce fertile offspring

Sympatric Speciation

speciation, organisms in same area cannot interbreed, differences in niche or behaviour

Sympatry

groups of organisms that live in the same geographical area

Stabilising Selection

Intermediate phenotypes have better advantages than extremes, occurs when environment is stable, genetic diversity in population decreases

Directional Selection

One phenotype has the best advantage, change in the environment or new advantageous allele

Disruptive Selection

Two or more phenotypes have better advantages, occur in environment that shows variation

Fossil record

preserved remains, shows simple early life, change = extinct ancestral forms evolved into modern species

Biogeography

distributions of lifeforms over geographical areas, related found close

Comparative Anatomy

groups organisms, show similar structural features, common ancestry

Molecular Biology

comparable shared molecular heritage, mutations accumulate, differences between comparable base sequences = evolutionary divergence

mtDNA and Y Chromosome Analysis

examine extent of genetic divergence due to unchanging