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48 Cards in this Set
- Front
- Back
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What is the study of Biogeography? |
the study of how organism are distributed geographical |
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Abiotic Factors |
No one species can survive in the full array of environmental conditions present on earth Temperature: has a big impact on the physiology of organisms, and organisms are limited in their ability to regulate their own temperatures. |
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Fitness-Trade offs: |
organisms tend to be adapted to a limited set of physical conditions, or abiotic factors - a particular temp etc. Every organism has a specific range of tolerance of abiotic conditions |
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Range |
geographical distribution |
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Biotic Factors |
The ability of a species to persist in a given is often limited by biotic factors - interactions with other organisms The distribution of organisms is determined not only by conditions present today but also by events in the past |
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Historical influences on present patterns |
The abiotic and biotic factors that influence the distribution of organisms are dynamic - they are constantly changing. Landforms and oceans that appear to be static have been in constant flux have an impact on dispersal - the movement of individuals from their place of origin to the location where they lie and breed as adults - they create opportunities for dispersal and introduce new biotic interactions on both continents |
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Wallace Line |
It separates species with asian and Australian affinities It exists because a deep trench in the ocean maintained a water barrier to dispersal, even when ocean levels dropped during the most recent glaciation Landforms on either side of the line remained isolated at a time when most of the other islands became connected caused plants and animals to the more Northern side to be racially different from the species on the western islands |
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The influence of humans |
Humans have transported thousands of plants, birds, insects, and other species across physical barriers to new locations - sometimes purposefully and sometimes by accident |
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Exotic Species |
One that is not native |
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Invasive Species |
an exotic species that is introduced to a new area which then spreads rapidly and competes successfully with the native species |
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Population |
a group of individuals of the same species that live in the same area at the same time |
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Population Ecology: |
the study of how and why the number of individuals in a population changes over time and space |
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What is Range? And what factors impact it? |
Abiotic: temperature, rainfall, the presence of geographical structures like mountains and oceans, and large scale ongoing and historical processes such as continental drift Biotic: past and current presence of other species that provide habitat, food, or competition Range is dynamic - in constant flux as abiotic and biotic factors change over time If a species range is small, it may consist of a single population of interbreeding individuals If a range is large it may consist of many populations - sometimes contiguous and sometimes isolated in space |
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Population Density |
the number of individuals per unit area |
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Different types of population density |
Random: the position of each individual is independent (ex. seeds are dispersed by the wind) Clumped: if the quality of the habitat is patchy or the organism associated in social groups (schools of fish) Uniform: If negative interactions occur among individuals such as competition for space, water, or other resources The particular dispersion pattern of a population has both proximate causes, in terms of physiological and behavioral mechanisms, and ultimate causes, in term of evolutionary adaption |
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Metapopulations |
a population of populations connected by migration, occurs when individuals from a species occupy many small patches of habitat, so that they form many independent populations Because humans are reducing large, contiguous areas of forest and grasslands to isolated patches or reserves, more and more species are being forced into a metapopulation structure |
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How to determine population size and density, or distribution pattern of individuals be determined? |
count the individuals that occur along lines of known position and length- transects -or inside rectangular plots- called quadrants- set up at random locations in the habitat Individuals within a population vary, and the populations are not static in time an space. |
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What 4 factors impact the number of idividuals in a population
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The number of individuals present in a population depends on four processes: birth, death, immigration, and emigration Populations grow as a result and births & immigration (individuals enter a population by moving from another) Populations decline due to death and emigration (individuals leave a population to join another) |
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Demography: |
the study of factors that determine the size and structure of populations through time |
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Age Structure: |
how many individuals of each age are alive In order to predict the future of a population ecologists need to know how likely individuals of different ages are to survive to the following year, how many offspring are produced by females and how many individuals of different ages immigrate and emigrate each generations |
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Generation |
the average time between a mothers first offspring and her daughters first offspring |
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Life Tables |
Summarize the probability that an individual will survive and reproduce in any given time interval ver he course of its lifetime. Biologists use life tables to study the demographics of endangered species Biologist focus on females when calculating life-table data, because the number of males present rarely affect population growth |
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Age Class |
a group of individuals of a specific age |
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Cohort |
a group of the same age that can be followed through time |
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Survivorship |
A key component of a life table - is defined as the proportion of offspring produced that survive, on average to a particular age. |
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Survivorship Curves and types |
using a logarithmic scale to see the patterns of survivorship Types of survivorship curves: Type I: Survivorship remains high throughout life - most individuals approach the species maximum life span (ex: Humans) Type II: Individuals have about the same probability of dying each year of life. Type III: extremely high death rates for seeds and seedling but high survival rates later in life |
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Fecundity |
The number of female offspring produced by each female in the population |
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Age-Specific Fecundity: |
The average number of female offspring produced by a female in each age class |
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Net Productive Rate: |
Indicates whether a population is increasing or decreasing (as long as immigration and emigration are insignificant) |
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Life History: |
Describes how an individual allocated resources to growth , reproduction , and activities or structures that are related to survival Life history is shaped by natural selection in a way that maximizes an individuals fitness in its environment In general, individuals from species with high fecundity tend to grow quickly, reach sexual maturity at a young age, and produce many small eggs or seeds. Individuals from species with high survivorship tend to grow slowly and invest resources in traits that reduce damage from enemies and increase their own ability to compete for water, sunlight, or food |
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Population Growth |
lFor conservation biologists, analyzing and predicting changes in population size is fundamental to managing threatened species A populations overall growth rate is a function of birth rates, death rates, immigration rates, and emigration rates. |
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per capita rate of increase |
The difference between the birth rate and the death rate per individual is called the per capita rate of increase and is symbolized by r. |
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Intrinsic rate of increase: |
occurs when birth rates per individual are as high as possible and death rates per individual are as low as possible - r reaches a maximum value |
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Population growth formula |
ΔN/Δt = rmaxN r max is a function of a species life history Each species has a characteristic r max that does not change but at any specific time, a population has an instantaneous growth rate, or per capita rate of increase, symbolized by r r is always less than r max |
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Exponential Growth Rate: |
occurs when r does not change over time The growth rate does not depend on the number of individuals in the population (DENSITY INDEPENDENT) Exponential growth adds and increasing number of individuals as the total number of individuals, N gets larger Circumstances: a few individuals found a new population in a new habitat a population has been devastated by a storm or some other type of catastrophe and then begins to recover, starting with a few surviving individuals It is not possible for exponential growth to continue indefinitely Growth is often density dependent |
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Logistic Growth & Carrying Capacity |
Carrying Capacity (K): the maximum number of individuals in a population that can be supported in a particular habitat over a sustained period time Depends on many factors: food, space, water, soil quality, and resting or nesting sites. Can change form year to year, depending on conditions Carrying capacity isn’t fixed and K varies among species and populations Equation: ΔN/Δt = rmaxN[(K-N)/K] Describes the logistic population growth: or changes in growth rate that occur as a function of population size. When N is small growth rate is high When N is large growth rate is low |
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Density-Independent Factors: |
alter birth rates and death rates irrespective of the number of individuals in the population (changes in abiotic environment: variation in weather patterns, or catastrophic events) |
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Density Dependent Factors: |
Change in intensity as a function of population size (biotic: when trees crowd each other they have less water, nutrients, and sunlight at their disposal and make fewer seeds) ` |
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population dynamics: |
changes in populations through time and space |
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How do metapopulations change through time? |
metapopulations are dynamic. Given enough time, each population within the larger metapopulation is expected to go extinct Migration from nearby population can reestablish populations in empty habitat fragments. THERE IS BALANCE BETWEEN EXTINCTION AND RECOLONIZATION |
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Why do some populations cycle? |
density-dependent factors can be based on intraspecific ( within species ) interactions, such as competition among members of cohort food, or interspecific (between species) interactions such as predation, parasitism, or competition among species for food. |
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Age Pyramids: |
Used to study age structures in our species. They use stacks of horizontal bars to plot the number of males and the number of females in each age cohort Analyzing an age pyramid can give biologists important information about a populations history. But studying age distributions can also help researchers predict a populations future. |
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Population “Momentum: |
Even though fecundity is predicted to decline there are so many young women that the overall number of births will stay high |
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Human Overpopulation |
The human population has increase dramatically in recent years. Humans are the primary cause of habitat loss and species extinction Overpopulation is also linked to declines in living standard, mass movements of people, political instability, and acute shortages of water, fuel, and other basic resources in many parts of the world. Now r may be undergoing the first long-term decline in history |
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Fertilely rates: |
the average number of surviving children that each women has durig her lifetime |
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Replacement rate: |
the average fertility required for each women to produce exactly enough offspring to replace herself and her offsprings father |
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Zero population growth: |
when the fertility rate is sustained for a generation r=o |
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Conditions to help Preserve Metapopulations |
Large population sizes Occupy larger geographical ranges closer to neighboring populations (more likely to be colonized) Have higher genetic diversity |
