Speciation Definitions PDF

Here are succinct definitions for each of the key terms and concepts related to speciation: Definitions of Terms and Concepts Allopatric\*\*: Refers to populations or species that are geographically separated, preventing gene flow between them. Allopatric Speciation\*\*: A process of speciation o...

Here are succinct definitions for each of the key terms and concepts related to speciation: Definitions of Terms and Concepts Allopatric\*\*: Refers to populations or species that are geographically separated, preventing gene flow between them. Allopatric Speciation\*\*: A process of speciation occurring when populations become isolated due to geographical barriers, leading to reproductive isolation and the emergence of new species over time. Biological Species Concept (BSC)\*\*: This concept defines a species as a group of populations whose members can interbreed and produce fertile offspring, emphasizing reproductive isolation as the key factor in species definition. Dispersal\*\*: The movement of individuals or populations away from their place of origin, which can lead to the colonization of new habitats and potentially result in speciation. Dobzhansky-Muller Incompatibility (DMI)\*\*: A genetic incompatibility that arises when two populations that have diverged accumulate different mutations, leading to reduced fitness of hybrids that carry alleles from both populations. Ecological Isolation\*\*: Occurs when two species exploit different resources or occupy different habitats within the same geographic area, limiting their interactions and reproductive opportunities. Ecological Speciation\*\*: A form of speciation that occurs when divergent selection based on different ecological niches leads to reproductive isolation between populations. Epistasis\*\*: A genetic interaction where the effect of one gene is modified by one or several other genes, influencing traits and potentially affecting speciation processes. Founder Effect\*\*: The reduced genetic diversity that occurs when a small group of individuals establishes a new population, potentially leading to rapid speciation as the founding population may not represent the genetic makeup of the original population. Genetic Conflict\*\*: A situation in which different genes or genetic elements within an organism exhibit conflicting interests, which can lead to evolutionary changes and influences on speciation. Haldane\'s Rule\*\*: A principle stating that when hybrid offspring between two species are produced, if one sex is absent, rare, or sterile, that sex is typically the heterogametic sex (e.g., males in animals with XY sex determination). Hybrid Zone\*\*: A geographic area where two or more populations meet and interbreed, resulting in the mixing of genetic material and the potential for gene flow between species. Introgression (Introgressive Hybridization)\*\*: The transfer of genetic material between species through hybridization and backcrossing, leading to the integration of genes from one species into the gene pool of another. Inversion\*\*: A chromosomal mutation where a segment of DNA is reversed end to end, which can affect gene expression and contribute to reproductive isolation in speciation. Isolating Mechanism\*\*: Any biological barrier that prevents gene flow between species, facilitating speciation by maintaining reproductive isolation. Parapatric\*\*: Referring to populations that are geographically adjacent but experience limited interbreeding due to differing environments. Parapatric Speciation\*\*: A type of speciation that occurs when two populations are adjacent to each other and diverge into separate species while still having a range of contact, often influenced by varying environmental pressures. Peripatric Speciation\*\*: A form of speciation that happens when a small population becomes isolated on the periphery of a larger population\'s range, leading to genetic divergence. Phylogenetic Species Concept (PSC)\*\*: Defines species based on their evolutionary history and a common ancestor, emphasizing unique genetic characteristics in the definition of a species. Postzygotic Barrier\*\*: A reproductive barrier that occurs after fertilization, preventing hybrid offspring from developing into viable or fertile adults. Prezygotic Barrier\*\*: A reproductive barrier that occurs before fertilization, preventing mating or fertilization between different species. Reciprocal Translocation\*\*: A chromosomal rearrangement where segments from two different chromosomes are exchanged, potentially leading to reproductive isolation. Reinforcement\*\*: A process in speciation where natural selection strengthens prezygotic barriers to reproduction in response to the production of less-fit hybrid individuals. Reproductive Isolating Barrier (RIB)\*\*: Any factor that prevents individuals of different species from mating or producing viable offspring, maintaining species boundaries. Reproductive Isolation\*\*: The mechanisms that prevent members of different species from interbreeding and producing fertile offspring, crucial for maintaining species distinctness. Secondary Contact\*\*: The scenario whereby previously isolated populations come back into contact, which can lead to hybridization, reinforcement of reproductive barriers, or further divergence. Segregation Distortion\*\*: A phenomenon where certain alleles increase their transmission to the next generation, leading to a non-Mendelian inheritance pattern that can influence speciation. Sexual Isolation\*\*: A type of reproductive isolation arising when species differ in their mating rituals or preferences, leading to reduced likelihood of mating. Sister Species\*\*: Closely related species that share a common ancestor and exhibit similar traits and evolutionary histories. Speciation\*\*: The evolutionary process through which populations evolve to become distinct species, typically involving reproductive isolation. Speciation Gene (and Speciation Trait)\*\*: Genes or traits that contribute directly to the reproductive isolation and divergence of populations, driving the speciation process. Speciation with Gene Flow\*\*: A scenario where speciation occurs without complete isolation, characterized by varying degrees of gene flow between populations while still resulting in reproductive isolation. Sympatric\*\*: Referring to populations or species that occupy the same geographic area and can potentially interbreed but do not due to reproductive barriers. Sympatric Speciation\*\*: A type of speciation that occurs within a single geographic area, where new species evolve from a common ancestor without physical barriers, often driven by ecological niches or behavioral shifts. Vicariance\*\*: A mechanism of allopatric speciation, where a population is split into separate groups due to the emergence of a physical barrier, such as the formation of a mountain range or river.