2. A researcher is studying the mating calls of a widespread species of cricket.
ID: 65862 • Letter: 2
Question
2. A researcher is studying the mating calls of a widespread species of cricket. He discovers that male crickets collected from different locations give different calls. Furthermore, females collected from different locations exhibit different responses to the calls, preferring the calls of males from the location they were collected from. The crickets are otherwise identical. In lab experiments, he demonstrates that females will not mate with males that have a call not typical of the location they were collected from, but if tricked, by playing calls of the appropriate male while another type of male is present, they will in fact mate, and these matings produce fertile offspring.
a) Are these crickets a single species, or a species complex? Is there an isolation mechanism? Explain?
b) Give at least two examples of species complexes composed of morphologically similar microspecies or cryptic species.
Explanation / Answer
a. The crickets are species complex which are similar species but the boundaries separate them. There exists a isolation mechanism due to which the crickets which belong to same species do not recognise the playing calls from a male which is from a different location.
b.a species complex is a group of closely related species very similar in appearance, such that boundaries between them are often unclear.
Self-pollination, vegetative propagation and aga-mospermous reproduction can lead to the genesis of taxa with continuous characters, which depending on the taxonomic treatment can either be recognized as individual species or defined together as a species complex. A cryptic species complex is a group of species that satisfies the biological definition of species, that is, they are reproductively isolated from each other but not reliably distinguishable morphologically. Species complexes can also be described as functional classes of organisms, which include taxonomic or ecological variants that replace one another across habitats or geographic regions, potentially providing advantages over individual species as indicators.
Agamospermous reproduction is also considered to be one reason why hundreds of microspecies have been described in genus and discrimination of these taxa is problematic. In addition, Alchemilla species are highly polyploid and the number of chromosomes varies even within a single species. It is presumed that most of the microspecies known probably result from relatively recent hybridisation events. Although morphological characters rarely resolve species complexes, one can find many examples in which morphological traits are used. As genesis of species complexes is often related to anomalies in the propagation system, in many cases characters used for discrimination of taxa in these complexes are associated with fertile parts of plants.
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