14.2 Community Interactions TEKS 12A The student is expected to: 12A interpret relationships, including predation, parasitism, commensalism, mutualism, and competition among organisms

14.2 Community Interactions TEKS 12A KEY CONCEPT Organisms interact as individuals and as populations.

14.2 Community Interactions TEKS 12A Competition and predation are two important ways in which organisms interact. Competition occurs when two organisms fight for the same limited resource. –Intraspecific competition –Interspecific competition

14.2 Community Interactions TEKS 12A Predation occurs when one organism captures and eats another.

14.2 Community Interactions TEKS 12A There are three major types of symbiotic relationships. –Mutualism: both organisms benefit

14.2 Community Interactions TEKS 12A –Commensalism: one organism benefits, the other is unharmed Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Organism benefits + Ø Ø Organism is not affected Commensalism There are three major types of symbiotic relationships.

14.2 Community Interactions TEKS 12A –Parasitism: one organism benefits, the other is harmed There are three major types of symbiotic relationships. Organism benefits 0 _ Organism is not affected Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. _ Parasitism + 0

14.2 Community Interactions TEKS 12A There are three major types of symbiotic relationships. –Parasitism meet their needs as ectoparasites (such as leeches) and endopaasites (such as hookworms)

14.3 Population Density And Distribution TEKS 7D, 12A The student is expected to: 7D analyze and evaluate how the elements of natural selection, including inherited variation, the potential of a population to produce more offspring than can survive, and a finite supply of environmental resources, result in differential reproductive success; 12A interpret relationships, including predation, parasitism, commensalism, mutualism, and competition among organisms

14.3 Population Density And Distribution TEKS 7D, 12A KEY CONCEPT Each population has a density, a dispersion, and a reproductive strategy.

14.3 Population Density And Distribution TEKS 7D, 12A Population density is the number of individuals that live in a defined area. Population density is a measurement of the number of individuals living in a defined space. Scientists can calculate population density.

14.3 Population Density And Distribution TEKS 7D, 12A Population dispersion refers to how a population is spread in an area. Geographic dispersion of a population shows how individuals in a population are spaced. Clumped dispersion Uniform dispersion Random dispersion

14.3 Population Density And Distribution TEKS 7D, 12A There are three types of dispersion. –clumped

14.3 Population Density And Distribution TEKS 7D, 12A There are three types of dispersion. –uniform

14.3 Population Density And Distribution TEKS 7D, 12A There are three types of dispersion. –random

14.3 Population Density And Distribution TEKS 7D, 12A Survivorship curves help to describe the reproductive strategy of a species. A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births.

14.3 Population Density And Distribution TEKS 7D, 12A Survivorship curves can be type I, II or III. –Type I—low level of infant mortality and an older population –common to large mammals and humans –Type II—survivorship rate is equal at all stages of life –common to birds and reptiles –Type III—very high birth rate, very high infant mortality –common to invertebrates and plants

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D The student is expected to: 11B investigate and analyze how organisms, populations, and communities respond to external factors; 12A interpret relationships, including predation, parasitism, commensalism, mutualism, and competition among organisms; 12D recognize that long-term survival of species is dependent on changing resource bases that are limited

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D KEY CONCEPT Populations grow in predictable patterns.

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Changes in a population’s size are determined by immigration, births, emigration, and deaths. The size of a population is always changing. Four factors affect the size of a population. –immigration –births –emigration –deaths

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Population growth is based on available resources. Exponential growth is a rapid population increase due to an abundance of resources.

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Logistic growth is due to a population facing limited resources.

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Carrying capacity is the maximum number of individuals in a population that the environment can support. A population crash is a dramatic decline in the size of a population over a short period of time.

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Ecological factors limit population growth. A limiting factor is something that keeps the size of a population down. Density-dependent limiting factors are affected by the number of individuals in a given area.

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Density-dependent limiting factors are affected by the number of individuals in a given area. –parasitism and disease –predation –competition

14.4 Population and Growth Patterns TEKS 11B, 12A, 12D Density-independent limiting factors limit a population’s growth regardless of the density. –unusual weather –natural disasters –human activities

14.5 Ecological Succession TEKS 11B, 11D, 12F The student is expected to: 11B investigate and analyze how organisms, populations, and communities respond to external factors; 11D describe how events and processes that occur during ecological succession can change populations and species diversity; 12F describe how environmental change can impact ecosystem stability

14.5 Ecological Succession TEKS 11B, 11D, 12F KEY CONCEPT Ecological succession is a process of change in the species that make up a community.

14.5 Ecological Succession TEKS 11B, 11D, 12F Succession occurs following a disturbance in an ecosystem. Succession regenerates or creates a community after a disturbance. –a sequence of biotic changes –damaged communities are regenerated –new communities arise in previously uninhabited areas

14.5 Ecological Succession TEKS 11B, 11D, 12F There are two types of succession. –primary succession — started by pioneer species

14.5 Ecological Succession TEKS 11B, 11D, 12F There are two types of succession. –secondary succession — started by remaining species