There are some conceptual and practical problems with the Biological Species Concept

There are some conceptual and practical problems with the Biological Species Concept

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
There are some conceptual and practical problems with the Biological Species Concept: Are species real or are they arbitrary categories imposed by biologists? Populations: where do they begin and end; often arbitrary and grade into other populations; Genus, Family, Order, etc. are these human constructs? Is a genus of bees = a genus of birds in terms of levels of organization? What are the typological grounds for the boundaries. What about "species" that can freely mate such as species of orchids that can mate sometimes between genera ( wide cross ). What about asexual species ? They don't reproduce with other species so every individual is a species?? Mayr would hold that species are real units. Views species boundaries as being defined by limits of gene exchange: each species is a group of populations held together by exchange of genes in a genetic system that allows free recombination among the chromosomes of this system. Holds that species are real
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: objective units with definable limits - basic units of evolution . No mistake that the Biological Species concept was advanced by two zoologists who worked with organisms that did not present some of the more obvious problem of plants and bacteria (Nevertheless, there is clear discontinuity in the phenotypes of bacteria). Isolating "Mechanisms" (misleading term: is it a mechanism in that it evolved for the purpose of isolating; or did isolating "mechanisms" evolve in one context and serve to prevent mating on another?). Premating mechanisms prevent interspecific crosses. Temporal or Ecological isolation (don't meet due to different time of emergence or occur in different habitats). Ethological (behavioral) isolation (meet but don't mate) e.g. fireflies. Mechanical isolation (can't transfer sperm, morphological incompatibilities). See table 15.1, pg. 405....
View Full Document

Ask a homework question - tutors are online