Population Ecology Flashcards

Question

What causes the shape and pattern of a predator prey graph

Answer 1

Predator graph always shadows prey graph Prey always reaches higher populations peaks than predators Because: As prey number increase predators increase because there is more food More numbers cause prey numbers to drop and then predator numbers drop because of decrease in foodless predators allows prey numbers to increase again Pattern repeats

Answer 2

Ecological niche: Each organism’s specific role to play in the community (and in its role it needs specific environmental conditions and resources in order to survive and reproduce)

Answer 3

Interaction between organisms that occurs when two or more individuals compete for the same resources

Answer 4

Intraspecific: competing individuals are of the same species and it always happens, particularly when population numbers are high Interspecific: two similar species have the same niches that overlap e.g: vultures and hyenas eat dead carcasses

Answer 5

Resource partitioning: ability for two competing species to co-exist in the same environment Example 1: Vulture and hyena both feed on dead carcasses but hyena can also kill their own and vultures are good at locating the carcasses by flying and good eyesight. They are able to do-exist without aggressively competing Example 2: Galapagos finches have different beak shapes and sizes to allow them to eat specific types of seeds, so several species of these finches can co-exist without competing for the same type of seed This is also an example of character displacement (adaptations that take place to eliminate competition)

Answer 6

Stratification to share light Plants needing most light grow fast and tall to get above all the other trees = canopy tress Trees and plants needing less light will grow under them = shorter tress and shrubs Mosses and ferns grow below everything completely in shade

Answer 7

When two species have identical niches, they cannot co-exist E.g bushbuck and Nyala - when nyala is introduced in a habitat the bushbuck eventually die out

Answer 8

The sequence of communities, where ie community replaces another over time, resulting in long term changes in the ecosystem

Answer 9

Pioneers (Mosses, lichens, grasses) are the first organisms that become established and they change the environment and make it suitable for complex organisms Climax community Is the stable ecosystem that develops after changes have occurred in the environment and it has become complex

Answer 10

Colonisers - lichens and mosses Pioneers - grasses Herbaceous plants - weeds Shrub - shrubs and bushes Climax trees - trees

Answer 11

Occurs when organisms settle in a habitat where there was previously no life Usually in areas where there was no soil (sand, lava flows, rock)

Answer 12

Occurs when organisms settle in a habitat which has been disrupted by human activities or natural disasters such as a fire Faster than primary succession because soil is already present and nutrients and seeds from previous growth

Answer 13

Social organisation: individuals in some species working together in order to increase their chances of survival Examples: Herds as a predator avoiding strategy Packs as a successful hunting strategy Division of tasks

Answer 14

Large herbivores graze in herds Many eyes and ears = detect predators easily Herds can scatter when there is a predator to confuse it Zebra run as a herd and their stripes create a confusing pattern Elephant and buffalo stand their ground and protect young ones in the middle

Answer 15

Wild dogs, hyenas and lions hunt in packs = co-operative hunting Advantages: higher success rate Can tackle larger prey Females with youngsters do not have to hunt but can take care of their offspring = reduces infant mortality

Answer 16

Eusocial animals: animals in which different species have particular roles or tasks Eusocial animals have groups/castes that perform specific functions in their colonies Examples of functions: finding food, caring for young, defence There is a queen who is the only fertile female and produces all the eggs Examples of eusocial animals: bees, ants, termites and wasps

Answer 17

Developments in medicine, including treatments and vaccinations Increases in agricultural productivity including mechanisation, disease resistant crops, fertilisers Better houses because of Industrial Revolution Increased understanding of how diet affects our health = Increased fertility Decreased mortality Increased longevity

Answer 18

The human demands placed on the environment

Answer 19

Amount of biologically productive land and water there is to regenerate the resources that humans use and to detoxify the waste that humans produce

Answer 20

Amount of land and water available to provide resources and absorb waste

Answer 21

Phenomenon whereby more resources and waste are created than what the earth can supply

Answer 22

Collapse of fish stocks Decreased forest covering Depletion of freshwater resources Excessive pollution Food insecurity

Answer 23

Arable land Grazing Forests Fossil fuel/mining land Fishing waters Built-up areas