ecology exam 3

1. Recreational- harvesting and fishing for sport
2. commercial- hunting and fishing for food production

the growth of a natural population from young individuals entering the population

MSY = maximum sustained yield
the sustainable rate at which individuals are harvested from a population without causing the population to decline.
The MSY is the point at which the arc on a graph is at its maximum (the tip of the arc).

Mallard nest success is positively correlated to rodent abundance rather than nesting density.

systematic nest searching: stringing ropes between atvs to flush ducks from nests in order to locate them and then checked the nests every week for hatch success

sherman live trapping: 7x7 trap grid measuring abundance of numbers of mice caught divided by number of trap nights

measured height and density of plants around nest sites for vegetation complexity

track plates and remote camera traps at nest sites to see what predators visited the nests and calculated #predator visits/# station nights

Exploitative: Using up resources first/faster than competitor.

Interference: Physically excluding competitors from accessing resources.

Gause’s principle states that two species can’t occupy the same niche and coexist, this leads to resource partitioning which has animals divide resources by space, time, and or behavior.

Migration, Herdingrouping, and birth synchrony. Herdingrouping affects predation because as predator density increases, prey group sizes increase. Prey group sizes increase as a form of protection against predators.

Both interactions occur between competing species, with the difference being how they influence resource acquisition. Exploitative interactions occur when a species uses a resource first or faster than its competitors. Like how some carnivores can more efficiently break down a carcass before other predators can use it. Interference interactions are when a competitor is physically excluded from accessing a resource. This can be seen when bears drive off wolves from their kills, preventing them from accessing the resource.

The fundamental niche is the set of resources and environmental conditions which, in the absence of competition, allow species to survive. The realized niche the actual niche that species occupy, which due to the presence of competitors, is a narrowed fundamental niche. Essentially the fundamental niche is a theoretical niche for a species to occupy, while the realized niche is the actual niche species occupy, which is influenced by competition.

Type 1: prey increases in proportion to prey density (linear)

Type 2: prey intake increases with density, but handling time levels the curve at certain abundances.

Type 3: Sigmoid (slow increase) developed from more prey becoming accessible for some reason or the predator develops a search image (adapts to hunt prey) which increases efficiency of predation. Levels off at the end due to handling time.

Wildebeest were believed to exclude antelopes, which led to wildebeest populations being reduced to protect antelopes. However, it was found that wildebeest did not affect antelope population, but zebra populations indirectly harmed antelopes by acting as prey to support predator populations.

Interspecific competition: Competition between DIFFERENT species.

A larger population size is more stable and has more room for error. Therefore, larger populations can be harvested and have decreased posibility of posing a threat to the decline of the population. Smaller populations would not be ideal to harvest from due to being sensitive to any change, given their population size, and possibly running them to extinction.

Migrating in large, synchronized groups allows species to avoid specialized predators that target smaller, slower groups. By herding, prey decrease their individual risk of being targeted by a predator. Predators may also be confused by the movement of many individuals, making it difficult to target one animal. Birth synchrony overwhelms predators, who can only eat a limited amount at a time and increases individual young survival rates.

One example would be male-biased harvesting, and the second would be older age-biased harvesting. For older-biased harvesting, harvest effort is directed at older individuals that are no longer reproducing. This causes a reduction in harvest yield and skews the population toward younger individuals which can disrupt social structures.

Obligatory relationships depend on one species for the survival of the other species (IE. Yucca moths depend on Yucca plants), where facultative mutualism is where a species can survive without the reliance of the other species (oxpeckers and mammals), but it is advantageous for both species to maintain the relationship.

A quota policy that will keep the same number of individuals to be harvested year per year would hurt the MSY in the long run by not allowing the population to recover. A quota of harvesting that can fluctuate with the carrying capacity will allow longevity of population.

The functional role & position of an organism in its community. Often defined by the resources used by animals.

overlap along one niche axis, but not along another niche axis.

two species cannot occupy the same niche & coexist. one will be excluded.

when one species alters habitat or creates a new one to the benefit of another species.

interaction where one species benefits to the detriment of another

Herbivory is parasitism-like when the plant survives — e.g., a deer browsing leaves or aphids tapping sap. The herbivore takes partial resources without killing the host, just like a parasite.
Herbivory is carnivory-like when the plant (or plant part) is killed outright — e.g., seed predation, where the entire embryo is destroyed and consumed, just like killing prey.