Introduction to Speciation quiz #4 Flashcards
Introduction to Speciation quiz #4
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How does the biological species concept define a species?
The biological species concept defines a species as a group of organisms that can interbreed and produce viable, fertile offspring, and are reproductively isolated from other such groups. What are prezygotic barriers in reproductive isolation?
Prezygotic barriers are mechanisms that prevent mating or fertilization between species, such as temporal, behavioral, or mechanical isolation. How does allopatric speciation occur?
Allopatric speciation occurs when populations are geographically separated, leading to genetic divergence and the formation of new species. What role does polyploidy play in sympatric speciation?
Polyploidy, the duplication of the entire set of chromosomes, can lead to instant reproductive isolation and speciation, especially in plants. What are the possible outcomes when species meet in a hybrid zone?
The outcomes can include reinforcement (strengthening reproductive barriers), fusion (species merge), or stability (hybrids persist without merging). What is fusion in the context of hybrid zones?
Fusion occurs when reproductive barriers weaken, allowing gene flow and causing two species to merge into one. How does speciation link microevolution and macroevolution?
Speciation acts as a bridge between microevolution (small genetic changes within populations) and macroevolution (large-scale evolutionary changes leading to new species). What is disruptive selection and how can it lead to sympatric speciation?
Disruptive selection favors individuals at both extremes of a trait, potentially leading to reproductive isolation and sympatric speciation within a population. What is the significance of nodes in a phylogenetic tree regarding speciation?
Nodes in a phylogenetic tree represent points where ancestral species split into two or more descendant species, marking speciation events. What is macroevolution and how is it related to speciation?
Macroevolution refers to large-scale evolutionary changes, such as the emergence of new species, which result from accumulated microevolutionary changes and speciation events. Why did Darwin avoid giving a strict definition of species in his book?
Darwin recognized the complexity and variability in defining species, noting that no single definition satisfied all naturalists. How can geographic isolation lead to the formation of new species?
Geographic isolation prevents gene flow between populations, allowing them to diverge genetically and form new species. How does gene flow affect the process of speciation?
Gene flow between populations can prevent speciation by homogenizing genetic differences, but reduced gene flow can promote divergence. Why are hybrids often less fit than parent species?
Hybrids may have reduced fitness due to genetic incompatibilities, leading to lower survival or reproductive success. What is an example of a postzygotic barrier?
An example is hybrid sterility, where offspring of two species are sterile, such as a mule from a horse and donkey. What is the importance of reproductive barriers in maintaining species integrity?
Reproductive barriers prevent gene flow between species, maintaining distinct species identities. What is the difference between reinforcement and fusion in hybrid zones?
Reinforcement strengthens reproductive barriers, while fusion weakens them, potentially merging species. How can environmental changes promote speciation?
Environmental changes can create new selective pressures or barriers, leading to divergence and speciation. How does the concept of species apply to asexual organisms?
The biological species concept is less applicable to asexual organisms, so other definitions based on genetic or ecological differences are used. How can human activities influence speciation?
Human activities can create new barriers or environments, promoting speciation, or increase gene flow, hindering it.
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