Integrative/systems Biology

Transcription

1 56 & 57 Topics Ecology as a Systems Biology Connection to Medicine Ecology definitions Population Ecology Community Ecology Ecosystem and Biosphere Ecology Ecology vs. Economic Sense Integrative/systems Biology From atom to biosphere - biological organization - components working together result in emergent properties complex interactions biodiversity works as a complex system Systems are not just sums of their parts - understanding systems needs holism rather than reductionism at every level of biological organization and at every scale of study e.g. metabolic networks not just pathways ecosystems not just populations or communities - INTERDISCIPLINARY RESEARCH - data mining and modeling Video Systems Biology Ecology is Systems Biology Why? How integrative is it? Systems biology to medicine Weil tal about integrative medicine Medicine also needs to be integrative Video integrative Medicine Video Healing with alternative means 1

2 Definitions Ecology - Study of interactions among organisms, and between organisms and their abiotic environment Environmental Science - Science of studying how humans interact with environment Population - Members of one sp. living in a given (researcher-defined) area at a given time 56 & 57: pp Community - All populations of all species interacting together in a defined area Ecosystem - Community plus the abiotic environment that the community interacts with Biosphere - Global ecosystem with all the communities on earth Population Ecology 56 & 57: pp Study of numbers of members in populations and population dynamics Interactions of a population with other populations, and the environment Reproductive success/failure Evolution of populations and population genetics Generates knowledge on managed biological resources such as forests, lakes etc. Rarest - One s presence doesn t matter to the other Most common Resources, Family/schooling, Defense, Limited seed spread, Asexual reproduction 56 & 57: pp Population Dispersion Population size vs. density - usefulness of density Severe competition (pecking on babies), territoriality 2

3 Population Size Changes 56 & 57: pp Population growth rate r = (b d) + (i e) Exponential growth curve Discuss characteristics of J type populations 56 & 57: pp Logistic growth curve over a longer period affected by environment Density-dependent factors and negative feedback 56 & 57: pp Generally biotic Predation Disease Competition (inter- and Intraspecific) Intra interference or exploitation Regulate population around a K 3

4 Survivorship curves 56 & 57: pp Shows probability of an individual s survival to a given age in a population or a cohort I Human, Bison II Rare some lizards III Oysters with several larval stages Survivorship Curves generalizations 56 & 57: pp Herring gull population Human Population 56 & 57: pp : 7.14 bill Projection S curve by the end of 21 st century 4

5 Human Populations 56 & 57: pp Thomas Malthus ( ) - human population cannot exponentially grow indefinitely - an idea contrary to many Human demographics - science dealing with human population statistics Human population size - may increase to unknown proportions due to uncertainty of carrying capacity for our species - however, birth rate decreased in the past 200 yrs. - drop in death rate is the main reason for population rise Age Structures 56 & 57: pp Predict future population growth Detect population growth momentum Environmental Degradation Related to population growth and resource consumption 56 & 57: pp Developed nations - consume more resources per capita, cause more environmental degradation People overpopulation - too many people living in a certain area - developing countries Consumption overpopulation - people over-utilizing resources - Highly developed nations, <20% of world population: 86% of all Al used, 76% timber harvested, 68% of energy produced, 61% of meat eaten and 42% of all water consumed - generates 75% of world s pollution and waste (data from older edition) 5

6 from: Mastney, Lisa, Purchasing Power: Harnessing institutional procurement for people and the planet. Worldwatch Paper 166 Sociobiology Studies behavior, especially social, as a character inheritable (at least partly) and affected by natural selection Seeks to explain behavior as a product of natural selection Behavior may help preserve one s genes in the population Video What is Sociobiology Insects and Humans Mention to E. O. Wilson in video Communities Many populations Community Ecology Have properties (collectively called comm. struct. and funct.) that population lacks Properties = Number of spp., relative abundance of each sp., types of interactions among spp., resiliency to disturbance, energy and nutrient flow throughout, productivity More difficult to study than population ecology 56 & 57: pp Three main types of interactions competition, predation and symbiosis 6

7 56 & 57: pp Connections of community to the size of an acorn crop Deer drawn to oak forest Increase in tick population Increase in human exposure to Lyme bacterium Public health hazard Bumper crop of acorns Increase in white-footed mouse population Decrease in gypsy moth pupae Healthier forest trees Each sp. has an ecological role within community = niche = influenced by physical, chemical and biological factors of the habitat Fundamental and realized niche 56 & 57: pp & 57: pp Competition Interspecific also in Comm. Ecology Interaction between individuals in their attempt to acquire same limited resource examples of resources? Two spp. with absolutely identical niches will not co-exist No two spp. indefinitely occupy same niche competitive exclusion possible by one reducing other s niche as in green and brown anoles Ability to cause less competition is adaptive Resource partitioning and character displacement reduce competition 7

8 Competition and Evolution Video 1 Competition or Cooperation Video 2 Legacy of Evolution Global Ecosystem 56 & 57: pp Resource partitioning Cape May warbler Blackburnian warbler Character displacement Finch sp. 1 Finch sp. 2 Bill depth Baybreasted warbler Yellow-rumped (Myrtle) warbler Black-throated green warbler Percentage of individuals of each size class Bill depth (mm) Predation - Predator avoidance adaptations 56 & 57: pp So many behavioral, mechanical, chemical characteristics Coloration displays Cryptic camouflage (prey or predator) Aposematic/warning coloration - Batesian, Müllerian mimicry Monarch Viceroy 8

9 Symbiosis 56 & 57: pp Intimate relationship between species Mutualism e.g. Rhizobium spp. and legume roots, Mycorrhizae, Zooxanthellae and coral Commensalism e.g. Social insects (army ants) and scavengers (millipedes, beetles, silverfish etc.), epiphytes Parasitism Host-parasite relationship - ecto- and endoparasites Succession and Climax Community development thru a series of stages of distinct community structures in a given area Pioneer community to climax community Primary succession (no soil at the beginning) Vs secondary succession (following disturbance) Climax is not static but stable, self sustaining and tolerant in Its environment discuss three panels in figure on left 56 & 57: pp Keystone species a species that has a disproportionately large effect on other spp., ecosystem or environment usually few vs most abundant Dominant species most abundant Video Wolves case MUST LISTEN 9

10 Ecosystem Ecology Systems Biology Topics Biomes Concepts of ecosystems/biosphere function Energy flow thru ecosystems How matter cycles thru ecosystems Carbon cycle Nitrogen cycle 56 & 57: pp Biomes 56 & 57: pp Large relatively distinct terrestrial regions with characteristic/same climate, soil, vegetation and animals irrespective of location Biome video 16 min Follow biomes in ch & 57: pp Three Main Concepts - Ecosystems Energy flows through ecosystems linearly Matter/nutrients moves in cycles through organisms to the abiotic environment and back into the organisms Abiotic environment impacts structural and functional adaptations - success of species 10

11 Energy Flow Through Ecosystems Energy - not reused by organisms - linear flow - defined by who eats whom Solar energy - trapped as chemical energy - photosynthesis Chemical energy released to do work - respiration Herbivores collect some of this chemical energy Carnivores and omnivores collect some of energy of herbivores Energy moves in complex webs not usually in simple chains/lines Draw and discuss an energy pyramid, trophic levels Trophic Levels in Food Webs Food webs - divided into trophic levels Primary producers - first trophic level Primary consumers - herbivores and omnivores - make up second trophic level Secondary consumers - carnivores and omnivores - third trophic level Tertiary consumers - higher order carnivores and omnivores Most energy - released as heat into environment Energy Flows Through Ecosystems 11

12 Food Web A deciduous forest food web Greatly simplified version of reality Species are lumped as groups, many links and spp. are not shown Biomass Pyramids A biomass pyramid shows an estimate of total mass of living material at each level (number pyramids show number of individuals at each trophic level) Dry mass (sometimes living mass or total volume) Important in sustaining trophic levels above Types of Biomass Pyramids 12

13 Producers - most biomass in most ecosystems - measured in grams dry weight per square meter Typically ~ 90% reduction from one trophic level to the other Inverted biomass pyramid - in very productive aquatic ecosystems where the algae turnover is very high Ecosystem Productivity Gross primary productivity (GPP) - total photosynthetic capture of energy Net primary productivity (NPP) = GPP R; Rate of incorporation of organic matter into producer tissue GPP and NPP - kilocalories per area per time, or as grams of carbon fixed Rate of productivity - affected by environmental factors Tropical rain forests - most productive terrestrial ecosystems Algal beds, coral reefs, swamp and marsh, estuaries - most productive aquatic ecosystems Humans consume ~40% of annual terrestrial NPP (25% of global NPP) Poisons/Pollutants and Trophic Levels DDT, PCBs, other toxins, pollutants - persistence - bioaccumulation - biomagnification Persistence - novel structures - organisms have not evolved schemes to breakdown metabolically Bioaccumulation - build up in fatty tissues Biomagnification - higher level consumers (e.g. sea gulls) have greatly increased tissue concentrations of pollutants 13

14 Matter Cycles Through Ecosystems 56 & 57: pp Biogeochemical cycles - cycles of matter between the abiotic and biotic components of the environment Earth - closed system - matter doesn t escape Carbon, nitrogen, phosphorus, water cycles - central to life on Earth Carbon, nitrogen, and water cycles have atmospheric components, and operate on a global scale Phosphorus has no atmospheric component, and cycles on a local scale Carbon Cycle 56 & 57: pp

15 56 & 57: pp Human Impact On Carbon Cycle Human activities disturb global carbon budget/balance Must see - Video Industrial Revolution - increased carbon dioxide in atmosphere by burning fossil fuels, deforestation etc. Increased atmospheric CO 2 - may cause catastrophic changes in climate, with global warming resulting in melting of the ice caps, global change in sea level, changes in precipitation, loss of arable land (and coastal cities), and mass extinction causing loss of biodiversity Nitrogen Cycle 56 & 57: pp Bacteria are essential to nitrogen cycle Nitrogen - abundant in atmosphere, a stable molecule - bacteria are needed to break it apart - this process consumes much energy Five steps are involved in the nitrogen cycle Nitrogen fixation Nitrification Assimilation Ammonification Denitrification Nitrogen Cycle 56 & 57: pp

16 Human Impact on N Cycle N fertilizers - leached and eroded - water pollution Fossil fuel combustion - N rapidly converted from organic materials to atmosphere 56 & 57: pp High temperatures of combustion - nitrogen oxides - severe pollution problems - photochemical smog Nitrogen oxides and water - nitrogen containing acids - acidify ground water, streams, lakes etc. Acidification - essential nutrients (Ca and K) - wash out of soil N 2 O (nitrous oxide) also depletes the atmospheric ozone layer 16