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Species definitions Flashcards

Species definitions
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  • Species
    A group of organisms capable of interbreeding and producing fertile offspring, defined by reproductive barriers, morphological traits, ecological niches, or shared ancestry.
  • Speciation
    The process where an ancestral species splits into two or more distinct species, often through mechanisms like geographic isolation or reproductive barriers, linking microevolution to macroevolution.
  • Microevolution
    Change in allele frequencies within a population over time, leading to small-scale evolutionary changes without forming new species.
  • Macroevolution
    Broad evolutionary changes that occur over long periods, leading to the emergence of new species and higher taxonomic groups, often involving significant morphological, ecological, or genetic shifts.
  • Allele
    A variant form of a gene at a specific locus on a chromosome, influencing distinct traits or characteristics in an organism.
  • Reproductive Isolation
    Mechanisms preventing different species from mating and producing viable offspring, including prezygotic barriers (e.g., behavioral differences) and postzygotic barriers (e.g., hybrid sterility).
  • Hybrid
    Offspring resulting from the mating of two different species, often sterile or non-viable, exemplifying post-zygotic reproductive barriers.
  • Prezygotic Barriers
    Mechanisms that prevent different species from mating and forming a zygote, including temporal, habitat, behavioral, mechanical, and gametic isolation.
  • Postzygotic Barriers
    Mechanisms that prevent hybrid offspring from surviving or reproducing, such as sterility or early death, ensuring that species remain distinct despite interbreeding.
  • Morphological Species Concept
    Defines species based on shared physical characteristics, both external and internal, rather than genetic or reproductive differences.
  • Ecological Species Concept
    Defines species based on their ecological niche, emphasizing their role and interactions within their environment, suitable for both sexual and asexual organisms.
  • Phylogenetic Species Concept
    Defines species as the smallest group of individuals sharing a common ancestor, identified by unique genetic traits on a phylogenetic tree, applicable to both sexual and asexual organisms.
  • Allopatric Speciation
    Speciation initiated by geographic isolation, where a population is divided by a physical barrier, leading to genetic divergence and the formation of new species over time.
  • Sympatric Speciation
    Speciation occurring within the same geographic area, often driven by factors like disruptive selection or polyploidy, leading to reproductive isolation without physical separation.
  • Polyploidy
    A condition where an organism has more than two complete sets of chromosomes due to errors in cell division, leading to genetic variation and potential speciation, especially in plants.