Mod 7, population interactions Flashcards

Question

nonliving vs living environmental components

Answer 1

Nonliving environmental factors include climate, the availability of water, and the concentration of minerals in the soil * Living environmental components consist of other organisms

Answer 2

Natural selection acts on phenotypes:  Natural selection does not act directly on genotypes of individual org.  Natural selection acts on phenotypes (structures and behaviors);  Selection of phenotypes affects genotypes present in a population’ Phenotypes and genotypes are closely tied.

Answer 3

Each population forms an integral part of a larger community, defined as a group of interacting populations  A community and its nonliving components of the area form an ecosystem  The biosphere is the enormous ecosystem that encompasses all of Earth’s habitable surface  Ecology is the study of the interrelationships of organisms with each other and with the nonliving environment

Answer 4

Density - The no. of individual organisms (N) in a given area (A) or volume (V). Expressed as an equation: DP = N/A or DP = N/V

Answer 5

Distribution of resources in an area 2. Interactions with other org

Answer 6

Individuals are distributed randomly throughout a suitable habitat and do not form any social group. - Occurs when resources are abundant and org. do not have to compete. e.g. trees and other plants in rain forests

Answer 7

Members of a population found in close proximity to each other. - usu. Congregate where food, water and shelter are abundant. Include: elephant herds, wolf packs, prides of lions, flocks of birds, schools of fish, humans and aspens Advantages of clumped distributions:  Many eyes to search for localized food;  Movement of group (e.g., schools of fish or flocks of birds) can confuse predators and  Predators may hunt in groups to bring down larger prey. © Pearson Education

Answer 8

Common among territorial animals defending resources or breeding territories  Territorial behavior is more common among animals during their breeding seasons E.G. Seabirds may space their nests evenly along the shore, just out of reach of one another.

Answer 9

Population size is how much and how fast a population is growing.

Answer 10

1. Births (b) 2. Immigration ( i ) decrease 3. Death (d) 4. Emigration (e)

Answer 11

Change in pop. Size = (births + immigration) – (deaths + emigration) (ΔN) = (b +i) - (d + e)

Answer 12

If birth rate exceeds death rate, the population growth rate is positive and population size increase If death rate exceeds birth rate, growth rate is negative and population size will decrease Immigration and emigration affect population size and also gene flow between populations.

Answer 13

Population Growth Rate (gr) The change in the no. of individuals in a pop. (ΔN) over a specific period (Δt). gr = ΔN Δt final value is negative if it has decreased

Answer 14

cgr = ΔN or N cgr = Nfinal - N N "Per capita" literally means "per head." This formula is often more useful than the gr because it tells you the contribution of the average individual to the population change. It allows you to compare the growth of a small pond of fish to a massive ocean of fish on equal footing.

Answer 15

Two main categories: 1. Biotic Factors – resources, disease and predators. 2. Abiotic Factors – floods, temperature and hurricanes.

Answer 16

Determines the maximum rate at which a population can grow. Biotic Potential is influenced by the following factors: - The age at which the org. first reproduces; - The frequency of reproduction; - The average no. of offspring produced each time; - The length of an org. reproductive life span and - The death rate of individuals

Answer 17

Exponential Growth = J-shaped, pop. Increases exponentially 2. Logistic Growth = S-shaped

Answer 18

A population growing at its biotic potential would grow Exponentially. Exponential Growth Pattern - Consists of a brief lag phase followed by a steep increase in growth. - Described as a J- shaped curve A population growing at its biotic potential will grow exponentially to form a J-shaped curve.

Answer 19

Exponential growth in natural populations is always temporary Exponential growth occurs in populations with boom-and-bust cycles — periods of rapid population growth are followed by a sudden, massive die-off — linked to changes in rainfall, temperature, or nutrient availability Ideal conditions encourage rapid growth; deteriorating conditions encourage massive die- off

Answer 20

Exponential growth in natural populations is always temporary Exponential growth may occur temporarily if environmental resistance is reduced In populations that do not experience boom-and-bust cycles, exponential growth may occur temporarily under special circumstances such as An increase of food supply or habitat A reduction in predation

Answer 21

lemming populations may grow until lack of food, large migrations, predators, or starvation cause sudden high mortality

Answer 22

Population size results from the interaction between biotic potential and environmental resistance and include: 1.Interactions among organisms such as predation and competition for limited resources 2. Natural events such as freezing weather, storms, fires, floods, and droughts Environmental resistance ensures that no natural population experiences exponential growth for very long

Answer 23

Populations that exhibit exponential growth eventually stabilize to match resources available As resources become depleted;  reproduction slows and growth rate drops to zero,  population size remain constant  result in Logistic Growth. Logistic growth occurs when new populations stabilize as a result of environmental resistance.

Answer 24

Environmental resistance include:  Interactions among org. such as predation and competition for limited resources and  Natural events such as freezing weather, storms, fires, floods, and droughts.

Answer 25

Growth pattern, populations increase to the max. and then stabilize  stabilize as a result of environmental resistance.  When plotted results in S-shaped growth curve, or S-curve; The maximum population size that can be sustained by an ecosystem is called its carrying capacity (K). In nature, an increase in population size (N) above carrying capacity (K) can be sustained for a short time

Answer 26

Carrying Capacity - No. of individuals in a population that can live in a given environment without depleting resources or harming themselves or the the habitat. Two factors that limit a habitat’s carrying capacity: 1. Density-independent factors - limit population size regardless of the population density. 2. Density-dependent factors - becomes effective as the population density increases

Answer 27

If a population far exceeds the carrying capacity of its environment >>>>> excess demands placed on the ecosystem >>>>destroy resources. — This can permanently and severely reduce carrying  capacity, causing the population to decline to a fraction of its former size or disappear entirely

Answer 28

becomes effective as the population density increases.  Exert a negative feedback on population size as the population density increases; Includes Predators, Parasites and Competition

Answer 29

limit population size regardless of the population density. Include: 1. Climate and Weather. - Insects and plants limited in size by the no. of individuals that can be produced before the first hard freeze. - Hurricanes, droughts, floods, and fire have an effect on population. 2. Human Activities - Pesticides and pollutants can cause decline in natural populations - Overhunting may lead to extinction - Habitat destruction by humans.

Answer 30

Predators exert density-dependent controls on populations Predators – org. that eat other organisms, called their prey which are killed directly and eaten. - becomes important as prey populations grow, - predator populations grow as their prey becomes more abundant.

Answer 31

Parasite – an org. that feeds on a larger organism (host) harming it. o Spread rapidly among dense populations; o Include tapeworms that live in the intestines, ticks and disease-causing microorganisms; o Parasites influence population size by weakening their hosts and making them susceptible to death; o Org. weakened by parasites are less likely to reproduce Parasites contribute to the death of less-fit individuals, producing a balance in which the host population is regulated but not eliminated

Answer 32

All organisms have limited resources to invest in their offspring and their own survival – No organism can produce endless offspring and provide extensive parental care for all of them Hence, life history strategies: -when to reproduce; - how many offspring to produce at a time; - how much energy and resources to devote to each offspring, Vary tremendously among species

Answer 33

The stability of a species’ environment * Mortality rate * Likelihood of multiple opportunities to reproduce before dying * Likelihood that a population can reach and remain at the carrying capacity of its environment

Answer 34

r-selected species * species live in a changing, unpredictable environment * unlikely to reach carrying capacity * have evolved characteristics that favor rapid reproduction * mature rapidly, have a short life span, produce a large no. of small offspring, and provide little parental care K-selected species * typically live in stable environments * develop populations that persist near the carrying capacity of their environment * mature slowly * have a long life span * produce small no. of large offspring * provide significant parental care or package significant nutrients along with the embryo * parental investment allows a higher percentage of offspring surviving to maturity

Answer 35

Competition * Predation * Parasitism * Mutualism * Commensalism Interactions classified according to whether each of the species is harmed or helped by the interaction

Answer 36

interspecific betyween a and b: harms both consumer prey: benefits a as the consumber, harms b mutualism: benefits both

Answer 37

Ecological niche is an organism’s physical home or habitat.  Includes all physical environmental conditions necessary for survival and reproduction of a species;  The physical and environmental conditions include: - Nesting or denning sites - Amt. of water needed - Climate - Type of nutrients - Optimal temperature range - pH and salinity - Degree of sun or shade it can tolerate

Answer 38

No two species ever occupy exactly the same ecological niche within the same natural community Competition occurs whenever two organisms attempt to use the same, limited resources

Answer 39

Intraspecific Competition: Members of the same population compete with each other for a limited resource, e.g. food, water, sunlight, soil nutrients, mates and breeding sites. Interspecific competition: Competition between members of two or more populations. As population densities increase and competition becomes more intense, some animals react by emigrating

Answer 40

Occurs between members of diff. species, if they feed on the same food or require similar breeding areas.  Exerts strong density-dependent environmental resistance, limiting population size  Occurs between zebra mussels and quagga mussels, who both consume phytoplankton

Answer 41

No two species can inhabit exactly the same ecological niche simultaneously and continuously. The Competitive Exclusion Principle (1934) by Russian biologist G. F. Gause states that: Two species with similar niches will compete for the same limited resource, eventually one will outcompete the other, and the species that is less adapted to the conditions will die out

Answer 42

Members of the same population compete with each other for a limited resource, e.g. food, water, sunlight, soil nutrients, mates and breeding sites.  One of the main factors driving evolution by natural selection;  Individuals better equipped to obtain resources are more likely to reproduce and pass their traits to offspring

Answer 43

interaction that involves a predator and a prey. Predators are org. that eat other org., called their prey. oAlthough predators often regarded as being carnivores (animals that eat other animals), ecologists sometimes include herbivores (animals that eat plants)

Answer 44

Predation – interaction that involves a predator and a prey. Predators are org. that eat other org., called their prey. oIn order to survive, predators must feed and prey must avoid becoming food Predators and prey have evolved colors, patterns, and shapes that resemble their surroundings, called Camouflage.  render plants and animals inconspicuous;  camouflaged animals tend to remain motionless;  animals closely resemble specific objects such as leaves, twigs, seaweed, thorns;  few desert plants evolved to resemble small rocks.

Answer 45

Some prey animals have evolved bright warning coloration – These animals may taste bad, inflict a venomous sting or bite (as bees or coral snakes do), or produce a big stink when bothered – The eye-catching colors seem to declare “Attack at your own risk!”

Answer 46

Predation - Mimicry Mimicry - members of one species having evolved to resemble another species. Batesian Mimicry – an adaptation whereby harmless animals to resemble venomous ones. e.g. the harmless hoverfly avoids predation by resembling a bee; Müllerian mimicry - a form of biological resemblance in which two or more unrelated noxious, or dangerous, organisms exhibit closely similar warning systems, such as the same pattern of bright colours – The scarlet king snake is protected by brilliant warning coloration that closely resembles the coral snake

Answer 47

Startle Coloration - animals deter predators. Include:  spots that resemble the eyes of a larger animal;  If predator gets close, prey flash its eyespots, startling the predator; allowing the prey to escape E.G. the peacock moth and the swallowtail caterpillar

Answer 48

Interaction in which one org. (parasite) derives its nutrients from another org. (host) which is harmed but not entirely consumed.  Differs from predation as the parasite often does not kill its host;  As density of host population increases, parasites pass easily between hosts;  Limit the reproductive and survival ability of the host;  Parasites are generally much smaller and more numerous than their hosts. E.G. tapeworms, fleas, ticks, and many types of disease-causing protists, bacteria, and viruses.

Answer 49

May be symbiotic and involve a close, long-term physical association between the participating species e.g. lichens form a mutualistic relationship between a fungus and an algae – The fungus provides support and protection while obtaining food from the photosynthetic alga

Answer 50

Begins with ecological disturbance (event that disrupts an ecosystem and change the biotic and abiotic environment);  Starts with a few hardy plants, called pioneers;

Answer 51

Keystone species – a specie that plays a major role in determining community structure  Exists only in a system where there is competition for a limited resource or a dominant competitor;  Not abundant;  If removed from the community, altered community interactions and relative abundance of other species.

Answer 52

Ecological Succession Community Interactions cause change over time. Succession - a gradual change in a community and its nonliving environment in which plants and animals replace one another . During succession: 1. Early org. modify the environment to favor later org.; 2. End-stage organisms suppress earlier org. but tolerate one another, producing a stable community 3. There is a general trend toward more species and longer-lived species. Ecological succession is the orderly, gradual, and predictable process of change in species structure within a community over time, often following disturbances.

Answer 53

Two (2) forms of succession: Primary and Secondary Primary Succession - community gradually forms in a location with no remnants of a previous community and no trace of life. - The disturbance may be a glacier or volcano eruption to produce a new island in the ocean or newly hardened lava on land Secondary Succession - a new community develops after an existing ecosystem is disturbed with remnants of the previous community (soil and seeds). E.g. beavers, landslides, or dam streams, causing marshes, ponds, or lakes to form. - Fire is a common disturbance that leads to secondary succession

Answer 54

alelle and genotype frequencies

Answer 55

number of indiviudlas over the area

Answer 56

$$\Delta N = (\text{Births} + \text{Immigration}) - (\text{Deaths} + \text{Emigration})$$

Answer 57

change in population size over time

Mod 7, population interactions Flashcards

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