The defecation reflex involves two postive feedback loops. these loops are the stretch receptors in the rectal walls and the sacral parasympathetic system. Defecation reflex empties the rectum by peristaltic movements push fecal matter from the sigmoid colon into the rectum. Then this distension of the rectal walls stimulates stretch receptors which results in defecation.
The first statement describes the environmental factor that affected the skipper butterflies.
When the birds became involved in the skipper butterflies ecosystem, they became a biotic environmental factor. The other answer choices are not environmental factors, but they are adaptations and examples of survival of the fittest.
Hope this helps! Good luck! :)
B. Tundra - only biome with snow
Complete question:
Two species of closely related frogs are found in the same pond high in the Andes of South America. Both species only have teeth on the top jaw. One has small teeth for holding small live prey prior to swallowing. The other species has very large sharp teeth for injuring and killing large prey prior to biting off pieces of flesh for consumption. The above is an example of:
- Directional selection
- Analogous structures
- Character displacement
- Hybridization
- Vestigial structures
Answer:
Explanation:
Competition is an ecological and evolutive process very common in nature. Competition might be intra- or interspecific. Competition between different species in a community or ecosystem might be due to the same resource use, or the same territory, shelter, etcetera. When a resource is useful for two or more species, and limited, they compete to gain it.
The principle of competitive exclusion states that different species with the same requirements sharing the niche can not coexist indefinitely based on the same limited resource. When <u>two competing species coexist, this is because of niche partitioning or niche differentiation</u>.
Differentiation of effective niche is closely related to <u>character displacement.</u>
<u>Character displacement</u> is the result of interspecific competition, in which two or more species that live in the same habitat manage to avoid competition by developing different traits. Morphological divergence, or any adaptative trait development, fixated genetically, is the product of niche segregation. Species tend to differentiate morphologically in the presence of strong competitors. Traits divergence favors coexistence in the same place.
In the exposed example, both species live in the same pond. But to avoid competition and competitive exclusion, species developed different teeth sizes to feed on different prey items.
Males tend to determine the sex of the baby depending on whether sperm is carrying and X or Y chromosome. An X chromosome combines with a mothers X chromosome to make XX (Girl). A Y chromosome from a male will combine with a mothers X chromosome to make an XY (Boy).
Males always pass on the Y chromosome
