![]() If the individual is female first, it is termed protogyny or “first female,” if it is male first, its termed protandry or “first male.” Oysters, for example, are born male, grow, and become female and lay eggs some oyster species change sex multiple times. Individuals of some species change their sex during their lives, alternating between male and female. In some species, sex is both genetic- and temperature-dependent. In some crocodiles, moderate temperatures produce males and both warm and cool temperatures produce females. In many turtles, cooler temperatures during egg incubation produce males and warm temperatures produce females. This is referred to as environmental sex determination, or more specifically as temperature-dependent sex determination. Binary fission and mitosis have similar results. Binary fissionBinary fission (BY-nuh-ree FIHSH-uhn) is the asexual repro-duction of a single-celled organism by division into two roughly equal parts. Sex determination in some crocodiles and turtles, for example, is often dependent on the temperature during critical periods of egg development. Binary Fission and Mitosis Most prokaryotes reproduce through binary fission. The sex of some species is not determined by genetics but by some aspect of the environment. Some fish, crustaceans, insects (such as butterflies and moths), and reptiles use this system. The W appears to be essential in determining the sex of the individual, similar to the Y chromosome in mammals. Homozygous for Z (ZZ) results in a male and heterozygous (ZW) results in a female. The XY system is also found in some insects and plants.Īvian sex determination is dependent on the presence of Z and W chromosomes. ![]() The presence of a Y chromosome causes the development of male characteristics and its absence results in female characteristics. Individuals homozygous for X (XX) are female and heterozygous individuals (XY) are male. Mammalian sex determination is determined genetically by the presence of X and Y chromosomes. Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed. The large arm, a fragment from another sea star, is developing into a new individual. \): Sea stars can reproduce through fragmentation. ![]()
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