Week 3: Species and Speciation

These flashcards cover key vocabulary and concepts relating to species definitions, concepts of speciation, and reproductive mechanisms in the context of biology.

Species Concept

A set of conditions that are necessary and sufficient to identify a group of individuals as a species.

Morphospecies Concept

Species delineations based on notable differences in phenotype

Biological Species Concept

Species delineations based on ability to successfully interbreed (offspring but be viable and fertile)

Ecological Species Concept

Species delineations based on niche usage and interactions with its enviornment

Phylogenetic Species Concept

Species delineations based on common ancestry

Differential Fitness Species Concept

Species delineation based on context specific adaptive traits

Practical Species Concept

Species delineations based on subjective judgement of a competent systematist

Allopatric Speciation

Populations are physically split apart and separated by a geographic barrier (ex. Mountains, rivers)and evolve into different species over time

The most common way that sub-divided populations can speciate

Sympatric Speciation

Populations evolve into new species in the same area but no physical separation occurs because there’s no barrier, often due to behavioural or genetic differences

The most controversial method of speciation

Parapatric Speciation

Populations live beside each other (no physical barrier) but different environments and selection pressures push them to evolve differently and over time stop inbreeding

Reproductive Isolating Mechanisms

These include various types that prevent species from interbreeding, such as temporal, ecological, and mechanical isolation.

Pre-Zygotic isolating mechanisms

Temporal, ecological, behavioural isolation, mechanical isolation

Post-zygotes isolating mechanisms

Gamete mortality. Hybrid in viability, hybrid sterility

Hybrid Sterility

A post-zygotic isolating mechanism where hybrids fail to produce viable offspring.

Gynogenetic Embryogenesis

A form of reproduction where the female's embryo requires activation by sperm from related species.

Niche

A particular set of resources in the environment that a species is adapted to.

Polymorphism

The occurrence of different forms among the members of a population.

Ancestral-Descendant Sequence

The historic lineage that traces back from modern organisms through their evolutionary history.

Gene Flow

The transfer of genetic variation from one population to another.

Phylogenetic Tree

A diagram that represents evolutionary relationships among various biological species or entities.

Species

A group of organisms that is biologically distinct from others and evolving along a lineage