individual

• Habitat


  Actual physical location where organisms making up a species live, described by its geographic, physical, chemical and biotic characteristics
• Environment


  Total set of conditions, biotic and abiotic, that surround and influence the biota and its habitat
• Niche concept


  • Joseph Grinnell - centered on the influences of the physical environment
  • Charles Elton - biological interactions as well as abiotic factors
  • G.F. Gause - interspecific competition
  • G. Evelyn Hutchinson - n-dimensional hypervolume
• Ecological niche


  • A role that a species plays in an ecosystem
  • Lifestyle or way of life
  • Can be defined by ranges of conditions and resources within which an organism can live
• Conditions and resources that define an ecological niche


  • Food it eats
  • Place in food web
  • How it gets food
  • Range of temperatures needed for survival
  • When and how it reproduces
• Fundamental niche


  Full range of resources or habitat a species could exploit if there were no competition with other species
• Realized niche


  Resources or habitat a species actually uses
• Ecological equivalents


  • Species that occupy similar niches but live in different geographical regions
  • Unrelated organisms that occupy similar habitats and resemble each other (e.g. owl & cat)
• Species


  • A group of individual organisms that interbreed and produce fertile, viable offspring
  • Members of the same species share both internal and external characteristics, which develop from their DNA
  • Organisms of the same species have the highest level of DNA alignment and therefore share characteristics and behaviors that lead to successful reproduction
• Types of species

  • Generalist - broad niches, can live in many different places, eat a variety of foods and tolerate a wide range of environmental conditions (e.g. flies, rodents, cockroaches, bullfrogs, humans)
  • Specialist - narrow niches, may be able to live in only one type of habitat, tolerate a narrow range of climatic & other environmental conditions, prone to becoming endangered (e.g. Koala and China's giant panda)
• General types of species

  • Native - normally live or thrive in a particular ecosystem
  • Nonnative/exotic/alien - migrate into or are deliberately or accidentally introduced in an ecosystem by humans
  • Indicator - serve as early warnings that a community or an ecosystem is being damaged (e.g. birds, fish, amphibians)
  • Keystone - roles are much more important than their abundance or biomass, critically linked to a large number of other species, loss of which can lead to population crashes and extinctions of other species that depend on it (e.g. sea otter - sea urchin - kelp)
• Evolution


  • Major driving force of adaptation to environmental change
  • Change in a population's genetic make-up through successive generations
  • Populations, not individuals, evolve by becoming genetically different
• Types of evolution


  • Microevolution - small genetic changes
  • Macroevolution - long-term, large-scale evolutionary changes among groups of species, wherein new species are formed from ancestral species and other species are lost through extinction
• Genetic variability

  Raw material of microevolution
• Genes


  Factors passed from parent to offspring, determine the physical characteristics that an organism inherits
• Alleles


  Different forms of a gene
• Individuals of a species share a unique set of inherited traits due to same genes
• Alleles of a shared trait are the basis of variation
• Mutation

  • Any change in the genetic material of a cell
  • Most mutations are neutral - does not stop the organism from surviving
  • Some can occur from exposure to mutagens (radioactivity, X-rays, natural and human-made chemicals)
  • Mutations have given rise to Earth's staggering biodiversity

  
• Gene flow


  Natural transfer of genes from one population into the genetic make-up of another through hybridization and inbreeding, results from chance dispersal and intentional migration
• Genetic drift


  A mechanism of evolution in which allele frequencies of a population change over generations due to chance, can have major effects when a population is sharply reduced in size by a natural disaster (bottleneck effect) or when a small group splits off from the main population to found a colony (founder effect)

  
• Natural selection


  • A process that occurs when some individuals of a population have genetically based traits that cause them to better survive and produce offspring
  • Three conditions necessary for evolution by natural selection to occur: natural variability for a trait in a population, trait must be heritable, trait must somehow lead to differential reproduction
• Adaptation/Adaptive trait


  Heritable trait that enables organisms to better survive and reproduce under a given set of environmental conditions
• Selective pressure


  Factor in a population's environment that causes natural selection to occur
• Behavior

  Apparent action an organism takes to adjust to environmental circumstance so as to ensure its survival, complex of 6 components: tropism, taxes, reflexes, instinct, learning, reasoning
• Do not confuse adaptation with acclimatization - when an organism becomes accustomed to changing environmental conditions, it is not the product of natural selection and there is no change in the gene pool of the species
• Artificial selection


  Selection by humans of desired traits in plants and animals
• Speciation


  Origin of new species, over numerous generations, new species arise by the accumulation of inherited variations, when a type is produced that is significantly different from the original, it becomes a species, a species can reproduce successfully with its own kind
• Adaptation


  • Complex of 6 components: Tropism, Taxes, Reflexes, Instinct, Learning, Reasoning
• Tropism


  • Phototropism
  • Gravitropism
  • Thigmotropism
• Animals


  • chemotaxis
  • rheotaxis
• Acclimatization


  When an organism becomes accustomed to changing environmental conditions, it is not the product of natural selection and there is no change in the gene pool of the species
• Acclimatization


  • Getting used to cold weather in winter
• Artificial selection


  The process of breeding plants and animals for particular genetic traits
• Speciation


  The origin of new species, where over numerous generations, new species arise by the accumulation of inherited variations
• Allopatric speciation


  Occurs when a population is divided into geographically isolated subpopulations, interrupting gene flow
• Sympatric speciation


  Occurs in populations that live in the same geographic area
• Circadian rhythm


  Physiological and behavioral characteristics that follow a daily, or circadian, pattern, with internal mechanisms that operate on an approximately 24 hour cycle
• Zeitgebers


  Any stimulus that resets the circadian rhythm, such as light/dark cycles, exercise, noise, meals, social activity, temperature, tides
• Photoperiod


  The interval in a 24-hour period during which an organism is exposed to light