Question

1. For each species white clover and three spine stickle back , give an example of density-dependent population regulation. Your answers should be specific enough that they can’t be the same for the two species. (4 pts)

any factors that could affect those two species

Answer 1

The three -spine stickleback (Gasterosteus aculeatus) is a fish native to most inland coastal waters north of 30 degree north.it has long been a subject of scientific study for many reasons. it shows a great morphological variation throughout its range, ideal for questions about evolution and population genetics. many populations are anadromous (they live in seawater but breed in fresh or backish water) and very tolerant of changes in salinity , it displays elaborate breeding behavior ( defending a territory, building a nest, taking care of the eggs and fry) and it can be social ( living in shoals outside the breeding season ) making it a popular subject of enquiry in fish ethology and behavioral ecology. Its antipredator adaptations, host-parasite interactions,sensory physiology, reproductive physiology, and endocrinology have also been much studied.

DENSITY DEPENDENT limiting factors cause a population's per capita growth rate to change- typically, to drop-with increasing population density.One example is competition for limited food among members of a population.

Identifying the causal factors underlying natural selection remains a key challenge in evolutionary biology.Although the genetic basis for the plate morph evolution of three spined stickleback is well described,There was a significant interaction of calcium with plate morph for fish from both regions, with complete morph sticklebacks growing more slowly at low calcium concentrations and low morph sticklebacks showing divergent responses to calcium concentration.