Untitled Flashcards Set

• Number of species in any given place is the most common measure of biodiversity, but can be a challenge

• Species richness is the number of species in a given area

  • Used to give an approximate sense of the biodiversity of a particular place

• Species evenness is the relative proportion of individuals within the different species in a given area 

  • Tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances

  • Is high is ecosystem’s species are all represented by similar numbers of individuals 

  • Is low if one species is represented by many individuals whereas other species are represented by only a few individuals 

• Phylogeny is the branching pattern of evolutionary relationships 

• More similar the traits of two species, the more closely related they are

• Range of tolerance 

  • The limits to the abiotic conditions that a species can tolerate 

  • Ex; extreme temperatures, humidity, salinity, pH

• Fundamental niche is the suite of abiotic conditions under which a species can survive, grow, and reproduce 

  • Establishes abiotic limits for the persistence of a species 

  • However, biotic factors can further limit the locations where a species can live 

    • Presence of competitors, predators, and diseases 

  • Biotic factors narrow the fundamental niche a species actually uses 

• Realized niche is the range of abiotic and biotic conditions under which a species actually lives 

• Determining what contributes to the realized niche, helps understand the distribution, areas of the world in which species live, of a species

• Niche Generalist is a species that can live under a wide range of abiotic or biotic conditions 

  • Can persist in changing conditions 

• Niche Specialist is a species that is specialized to live in a specific habitat or to feed on a small group of species 

  • Persist quite well when conditions are constant, but vulnerable to extinction 

• Average life span of a species is about 1 million to 10 million years 

  • 99% if the species that have ever lived on Earth are extinct 

• The fossil record has noted 5 periods of global mass extinctions 

• Greatest mass extinction took place 251 million years ago

  • Roughly 90% of marine species and 70% of land vertebrates went extinct 

• Dinosaurs went extinct at the end of the cretaceous period(65 million years ago) 

  • Caused by a meteorite and resulted in a large dust cloud, halting photosynthesis 

• A 6th mass extinction is currently in place 

  • 800 extinctions over the past 400 years 

• Earth’s biodiversity is the product of evolution

  • Microevolution is evolution below the species level

  • Macroevolution is evolution that gives rise to new species, genera, families, classes, or phyla 

    • Speciation is restricted to the evolution of new species 

• Genes are physical locations on chromosomes within each cell of an organism 

• Complete set of genes in an individual is called its genotype 

• An individual’s phenotype is the actual set of trays expressed in that individual 

  • Color of your eyes 

• Most phenotypes are the result of an individual’s environment, a well its genotype 

• Environmental factors can cause mutations 

  • UV radiation 

• Recombination is the process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division 

  • Does not create new gene, but brings together new combinations of alleles on a chromosome 

• Evolution by artificial selection 

  • The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind 

• Evolution by natural selection 

  • The process in which the environment determines which individuals survive and reproduce 

• Key ideas of Darwin’s theory 

  • Individuals produce an excess of offspring 

  • Not all offspring can survive 

  • Individuals differ in their traits 

  • Difference in traits can be passed on from parents to offspring 

  • Differences in traits are associated with differences in the ability to survive and reproduce 

• Natural selection factors any combination of traits that improves an individual’s fitness

  • Ability to survive and reproduce 

  • Traits that improve an individual’s fitness is called an adaptation 

• Evolution can also occur by 5 random processes: 

  • Mutation 

  • Gene flow 

    • Process by which individuals move from one population to anther and thereby alter the genetic composition of both populations 

    • Can be helpful to bringing genetic variation into a population 

  • Genetic drift 

    • Change in the genetic composition of a population over time as a result of random mating 

  • Bottleneck effect 

    • Reduction in the genetic diversity of a population caused by a reduction in its size 

    • Can cause extinction 

  • Founder effect 

    • Change in the genetic composition of a population as a result of descending from a small number of colonizing individuals 

• Geographic isolation 

  • Physical separation of a group from individuals from others of the same species 

• Allopatric speciation 

  • Process of speciation that occurs with geographic isolation 

• Reproductive isolation 

  • Result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring 

• Sympatric speciation 

  • Evolution of one species into two, without geographic isolation 

  • Usually happens through process called polyploidy 

    • Number of chromosomes is increased 

• Evolution occurs more faster in genetically modified organisms 

  • Organism produced by copying genes from a species with a desirable trait and inserting them into another species 

Chapter 3

• Disturbance 

  • An event caused by physical,chemical, or biological agents, resulting in changes in population size or community competition 

    • Tsunamis, tornadoes, hurricanes, ice storms, etc

  • Can be caused due to anthropogenic causes

    • Human settlements, agriculture, air pollution, etc.

• Not every ecosystem disturbance is a disaster 

  • Although the population of a species might  be diminished, the net primary productivity of all producers in an ecosystem may stay the same

• Resistance of an ecosystem is a measure of how much disturbance can affect flows of energy and matter

  • When a disturbance influences populations, but has no effect on the overall flow of energy and matter; high resistance 

• Resilience is the rate at which an ecosystem returns to its original state after a disturbance 

  • Depends on specific interactions of the biogeochemical and hydrologic cycles 

• Restoration ecology is the study and implementation of restoring damaged ecosystems 

  • Restoration ecologists are currently working on two main projects: Florida everglades and Chesapeake bay 

• Scientists commonly conduct studies in a watershed

  • All land in a given landscape that drains into a particular stream,river, or wetland

• Intermediate disturbance hypothesis 

  • Hypothesis that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance labels 

  • Highest levels of diversity can occur when ecosystems experience an intermediate frequency of disturbance 

Chapter 6

• Ecological succession is the predicable replacement of one group of species by another group of species over time 

• Primary successions is ecological succession occurring on surfaces that are initially devoid of soil 

• Secondary succession is the succession of plant life that occurs in areas that have been disturbed but have not lost their soil 

• Pioneer species can colonize new areas rapidly and grow well in full sunshine 

• Climax community is described as the final stage of succession 

• In a biome, the number and types of species are determined by 3 factors 

  • Latitude 

    • As we move from the equator toward the north pole, the number of species declines 

  • Time

    • The longer a habitat exists the more colonization, speciation, and extinction can occur in that habitat 

  • Habitat size and distance from a source of species

    • Factors are basic for the theory of island biogeography 

      • Demonstrates the dual importance of habitat size and distance in determining species richness

    • Large habitats contain more species 

      • 1. Dispersing species are more likely to find larger habitats 

      • 2. Larger habitats can support more species 

      • 3. Larger habitats contain a wider range environmental conditions 

    • Distance matters because while many species can disperse short distances, only a few can disperse long distances

• Population 

  • Individuals that belong to the same species and lube un a given area at a particular time 

• Community 

  • All the populations of organisms within a given area 

• Individual -> Population -> Community -> Ecosystem -> Biosphere 

• Population density 

  • Number of individuals per unit area at a given time 

  • Helps scientists determine whether a species is rare or abundant 

• Sex ratio is the ratio of males to females in a population 

• Age structure is the description of how many individuals fit into a particular age category in a population 

• Limiting resource is a resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size 

• Density-dependent factor influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population 

• Density-independent factors have the same effect on an individual’s probability of survival and amount of reproduction at any population size 

• Population growth rate is the number of offspring an individual can produce in a given time minutes the deaths of the individual or its offspring during the same period 

• Intrinsic growth rate is the max potential for growth of a population under ideal conditions with unlimited resources 

• Overshoot is when a population becomes larger than the environment’s carrying capacity 

• Die-off is a rapid decline in population due to death 

• K-selected species is a species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity 

  • Large organisms, produce few offspring 

  • Elephants

• r-selected species 

  • Has high intrinsic growth rate, which often leads to population overshoots and die-offs

• Survivorship curve 

  • Graph that represents the distinct patterns of species survival as a function of age 

• Type I survivorship curve 

  • Pattern of survival over time in which there is a high survival rate throughout most of the life span, but then individuals start to die in large numbers as they approach old age 

• Type II survivorship curve 

  • A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span 

• Type III survivorship core 

  • Pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood 

• Corridor is a strip of natural habitat that connect populations 

• Metapopulation is a group of spatially distinct populations that are connected by occasional movements of individuals between them 

• Inbreeding depressions is when individuals with similar genotypes-relatives- breed with each other and produce offspring that have an impaired ability to survive and reproduce