Search results
Results From The WOW.Com Content Network
[15] [16] A structure can be homologous at one level, but only analogous at another. Pterosaur, bird and bat wings are analogous as wings, but homologous as forelimbs because the organ served as a forearm (not a wing) in the last common ancestor of tetrapods, and evolved in different ways in the three
Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent and have evolved, usually divergently, from a shared ancestor. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales.
These structures are the future scrotum and labia majora in males and females, respectively. The genital tubercles of an eight-week-old embryo of either sex are identical. They both have a glans area, which will go on to form the clitoral glans (females) or penile glans (males), a urogenital fold and groove, and an anal tubercle.
Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions.
All vertebrate forelimbs are homologous, meaning that they all evolved from the same structures. For example, the flipper of a turtle or of a dolphin, the arm of a human, the foreleg of a horse, and the wings of both bats and birds are ultimately homologous, despite the large differences between them. [1]
Sequences are either homologous or not. [3] This involves that the term "percent homology" is a misnomer. [4] As with morphological and anatomical structures, sequence similarity might occur because of convergent evolution, or, as with shorter sequences, by chance, meaning
It is common for significant homology to be conserved, with matching structures forming from matching primordia, and having the same evolutionary origin. However, even if structures are almost physically and functionally identical, they may not be homologous; their analogous functions and appearance might be the product of convergent evolution.
The bulk of that nose is composed of two large, fatty structures, the spermaceti organ and the "junk". The junk is structurally the same as the melon (homologous to it). The melon is not homologous to the spermaceti organ. [1] [5] Research on the expression of genes such as that for the protein MYH16 show it originates from the masseter muscle. [6]