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Ovuliparity means the female lays unfertilised eggs (ova), which must then be externally fertilised. [10] Examples of ovuliparous fish include salmon, goldfish, cichlids, tuna and eels. In the majority of these species, fertilisation takes place outside the mother's body, with the male and female fish shedding their gametes into the surrounding ...
Fish embryos go through a process called mid-blastula transition which is observed around the tenth cell division in some fish species. Once zygotic gene transcription starts, slow cell division begins and cell movements are observable. [4] During this time three cell populations become distinguished. The first population is the yolk syncytial ...
By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce [1] and organisms only pass on 50% of their genes. [2]
The synchronous spawning of many species of coral in marine reefs means that inter-species hybridization can take place as the gametes of hundreds of individuals of tens of species are liberated into the same water at the same time. Approximately a third of all the possible crosses between species are compatible, in the sense that the gametes ...
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
Pacific salmon are semelparous or "big bang" spawners, which means they die shortly after spawning Bottarga, the pickled and dehydrated roe of mullet. Marine animals, and particularly bony fish, commonly reproduce by broadcast spawning. This is an external method of reproduction where the female releases many unfertilised eggs into the water.
Nuptial tubercles or breeding tubercles (also called pearl organs or nuptial efflorescence) are noticeable skin roughness or horny nodules that form on male fish during breeding. They are made of keratin, the same material as hair, hooves, and fingernails.
Fisheries-induced evolution differs from the Darwinian evolution model by virtue of the direct human factor. [2] For FIE, fishing enforces a greater selection pressure for traits, often through sheer effort and catch numbers, which can disparage natural selection pressures such as predator-prey interactions and environmental influences.