Macroevolution – Evolution of Phenotypes (Lecture #5)

Vocabulary flashcards covering key terms and concepts from the lecture notes on speciation, reproductive isolation, and adaptive radiation.

Biological species concept

A species is a group of interbreeding natural populations that are reproductively isolated from other such groups.

Morphological species concept

A species defined by morphological similarities and differences, often used when reproductive data are unavailable.

Ecological (niche) species concept

A species defined by its ecological niche and adaptations to a particular set of resources.

Phylogenetic species concept

A species defined as the smallest monophyletic group on a phylogenetic tree.

Phenotype

Observable characteristics or traits of an organism.

Genotype

Genetic makeup underlying the phenotype—the alleles an individual carries.

Reproductive isolation

Biological barriers that prevent interbreeding between populations, maintaining separate gene pools.

Prezygotic barriers

Barriers that prevent fertilization before a zygote forms.

Habitat isolation

Prezygotic barrier where populations occupy different habitats and rarely meet.

Temporal isolation

Prezygotic barrier due to mating or flowering at different times.

Behavioral isolation

Prezygotic barrier due to differences in courtship rituals or signals.

Mechanical isolation

Prezygotic barrier due to incompatible reproductive parts.

Gametic isolation

Prezygotic barrier where gametes (sperm and egg) cannot fertilize.

Postzygotic barriers

Barriers that reduce viability or fertility of hybrids after fertilization.

Reduced hybrid viability

Hybrids have lower survival rates to reproductive age.

Reduced hybrid fertility

Hybrids are sterile or have greatly reduced fertility.

Hybrid breakdown

Hybrid offspring are viable/fertile in the first generation but show reduced fitness in subsequent generations.

Allopatric speciation

Speciation that occurs when populations are geographically separated by barriers.

Geographic isolation

Physical separation of populations by geographic barriers (mountains, rivers, etc.).

Founder effect

Genetic drift in a small founder population leading to rapid divergence.

Genetic drift

Random fluctuations in allele frequencies, especially impactful in small populations.

Sympatric speciation

Speciation without geographic isolation; can involve intrinsic barriers like polyploidy or ecological differentiation.

Polyploidy

Having more than two complete sets of chromosomes; can cause instant reproductive isolation.

Niche

Exploitable role or position of an organism in its environment, including resource use.

Adaptive radiation

Diversification of a lineage into many species from a common ancestor, often after colonization of new habitats.

Evolutionary tree

A branching diagram showing patterns of descent from a common ancestor.

Homologous character

A trait shared by related groups due to common ancestry (not convergent evolution).

Common ancestor

The ancestral species from which two or more lineages diverged.

Sexual selection

A form of natural selection where traits affecting mating success influence reproductive success.

Hybrid zone

Geographic area where members of different species meet and interbreed, producing hybrids.