Topic 14 - Biosphere and Ecology PDF

Topic 14 Biosphere and ecology Learning Outcomes Determine which abiotic factors influence the presence of species in certain ecosystems and biomes Associate biological structures, patterns or mechanisms with a specific level of ecological research Explain how and why abiotic factors c...

Topic 14 Biosphere and ecology Learning Outcomes Determine which abiotic factors influence the presence of species in certain ecosystems and biomes Associate biological structures, patterns or mechanisms with a specific level of ecological research Explain how and why abiotic factors can differ between two distinct habitats Determine if changes in range distribution results from evolutionary history, biotic factors or abiotic factors. Compare characteristics of two species based on their resource utilization Predict the range expansion of a species upon changes in abiotic factors Using an example, explain how ecological changes can affect evolutionary changes Classify biological interactions based on the benefit or harm for each species Design a simple experiment that can measure the difference between a fundamental and a realized niche 2 https://www.wooclap.com/BIO1130 3  Topic 14 Biosphere, ecology and conservation biology 14.1 – The biosphere What is ecology? Ecology: The study of how organisms interact with each other and their environment These interactions depend on… Biotic factors (other organisms in the environment) Abiotic factors (physical and chemical properties of the environment) These interactions determine the… Geographical distribution of species Abundance and diversity of organisms Evolutionary processes Movement of energy and materials in living ecosystems Successional development of ecosystems 5 What is ecology? Ecology looks at many levels of biological hierarchy 6 What is ecology? Ecology looks at many levels of biological hierarchy How organism structure, physiology and behaviors respond to the environmental challenges. 7 What is ecology? Ecology looks at many levels of biological hierarchy How organism structure, physiology and behaviors respond to the environmental challenges. Population: group of individuals of the same species living in an area How biotic and abiotic factors affect population size and how it changes through time. 8 What is ecology? Ecology looks at many levels of biological hierarchy How interactions between species (predation, competition, mutualisms…) affect community structure and organization. How organism structure, physiology and behaviors respond to the environmental challenges. Community: group of populations of different species in an area How biotic and abiotic factors affect population size and how it changes through time. 9 What is ecology? Ecology looks at many levels of biological hierarchy How interactions between species (predation, competition, mutualisms…) affect community structure and organization. How organism structure, physiology and behaviors respond to the environmental challenges. Ecosystem: Community of organisms in an area and the physical factors with which those organisms interact How energy and chemicals cycle between organisms and the environment. How biotic and abiotic factors affect population size and how it changes through time. 10 What is ecology? Ecology looks at many levels of biological hierarchy What factors control exchanges of energy, material and organisms across multiple ecosystems and how. How interactions between species (predation, competition, mutualisms…) affect community structure and organization. How organism structure, physiology and behaviors respond to the environmental challenges. Landscape: mosaic of connected ecosystems How energy and chemicals cycle between organisms and the environment. How biotic and abiotic factors affect population size and how it changes through time. 11 What is ecology? Biosphere (global ecosystem): sum of all planets’ ecosystems and landscapes Ecology looks at many levels of biological hierarchy What factors control exchanges of energy, material and organisms across multiple ecosystems and how. How interactions between species (predation, competition, mutualisms…) affect community structure and organization. How organism structure, physiology and behaviors respond to the environmental challenges. How the regional exchange of energy and materials influences the functioning and distribution of organisms across the biosphere How energy and chemicals cycle between organisms and the environment. How biotic and abiotic factors affect population size and how it changes through time. 12 Earth climate and dynamics Climate: long-term weather conditions in a given area à first cause of organisms distribution on earth Determined by 4 physical factors: temperature, precipitation, light, wind The solar energy input varies at the surface of the earth, causing great latitudinal variations and gradients of those factors. 13 Earth climate and dynamics Climate: long-term weather conditions in a given area à first cause of organisms distribution on earth Determined by 4 physical factors: temperature, precipitation, light, wind The solar energy input varies at the surface of the earth, causing great latitudinal variations and gradients of those factors. Moist Arid 14 Biomes Biome: major ecosystem type, classified according to the predominant vegetation (terrestrial) and the physical environment (aquatic), and characterized by adaptations of organisms to that environment. 15 Biomes Biome: major ecosystem type, classified according to the predominant vegetation (terrestrial) and the physical environment (aquatic), and characterized by adaptations of organisms to that environment. Biomes have specific compositions of organisms and differ in: average temperature/precipitation seasonal variations soil nutrients composition… ph Climogra 16 Biomes Deep lakes do not display water mixing (surface ↔ bottom) à meromictic lakes (e.g. Pink lake, Gatineau Park) Thermoclines (vertical gradients in temperature) that prevent water mixing: à deep cold-water (bottom) and upper warm-water (surface). à Turnover in temperate holomictic lakes that moves oxygenated surface water to the bottom and nutrient-rich bottom water to the surface in the spring and fall. 17  Topic 14 Biosphere, ecology and conservation biology 14.2 – Species distribution Species distribution Where do species occur and why? à The distribution of a species depends on its evolutionary history, on biotic factors and on abiotic factors. Diversification of finches in the Galapagos islands due to the colonization of different islands and specialization on different seeds à adaptation to new Diversification of cichlids in resources Africa due to alternating deep à ecological speciation and shallow lakes à adaptation to new habitats Brawand et al 2014 Grant et al 1981 à ecological speciation 19 Species distribution Where do species occur and why? à The distribution of a species depends on its evolutionary history, on biotic factors and on abiotic factors. Costello et al 2017 Marine species richness Chlorophyll production Costello et al 2017 Mannion et al 2014 Extant terrestrial vertebrate species richness Vascular plant species richness Mutke et al 2010 20 Species distribution E x ta n t te rrestrial ve species ri chness rtebrate Why are there more species in the tropics? Species richness: number of species in a biological community. à increase (more speciation or less extinction). 3 hypotheses based on climate/evolutionary history can explain the latitudinal gradient in species richness: 1. Tropical latitudes receive more solar energy than temperate zones à with much longer growing season à higher productivity à ↑ biodiversity. 21 Species distribution E x ta n t te rrestrial ve species ri chness rtebrate Why are there more species in the tropics? Species richness: number of species in a biological community. à increase (more speciation or less extinction). 3 hypotheses based on climate/evolutionary history can explain the latitudinal gradient in species richness: 2. Fewer seasonal changes in tropical regions (more stable climate) à high competition throughout the year… à leading to ↑ niche specialization and resource partitioning between species à each species therefore occupies a smaller niche (there are more specialists than generalists) à ↓ competition à ↑ biodiversity. 22 Species distribution E x ta n t te rrestrial ve species ri chness rtebrate Why are there more species in the tropics? Species richness: number of species in a biological community. à increase (more speciation or less extinction). 3 hypotheses based on climate/evolutionary history can explain the latitudinal gradient in species richness: 3. During the ice age, temperate communities were vulnerable to glaciations à tropical communities are typically older and stayed undisturbed for longer à reduced extinction rates in the tropics. à ↑ biodiversity 23 Species distribution E x ta n t te rrestrial ve species ri chness rtebrate Why are there more species in the tropics? Species richness: number of species in a biological community. à increase (more speciation or less extinction). 3 hypotheses based on climate/evolutionary history can explain the latitudinal gradient in species richness: 3. During the ice age, temperate communities were vulnerable to glaciations à tropical communities are typically older and stayed undisturbed for longer à reduced extinction rates in the tropics. à ↑ biodiversity Diversification in mammals (Rolland et al. 2014) 24 Response to environmental stress Specialist Performance Species can vary greatly in the type of resource they use. Generalist: species that thrives in a wide variety of environmental conditions (use different resources). Generalist E.g. an racoon with a varied diet (berries, insects, small animals). Resource Specialist: species that thrives only in a narrow range of environmental conditions (uses very specific resources). E.g. a koala feeding almost exclusively on eucalyptus leaves. The abundance of an organism reaches a theoretical maximum at some optimal value across an environmental gradient. à Actual abundance curve differs from the potential abundance curve because of biological interactions. 25 Dispersal and species range Dispersal: movement of individuals away from the area of origin or from centers of high population density Ex: Wood turtle (Glyptemys insculpta) à expanded its natural range (↑ in T°C after glaciers retreated). The species range did not expand south because of the limit in 2 1 1 temperature or in some island because of the limit in salinity tolerance The current species distribution is fragmented because of new urban areas à The realized distribution is smaller than the potential suitable range. 26 Dispersal and species range Species living along an environmental gradient can respond to climate change in various ways: A. Natural range limited by physiological factors. B. Natural range is shifted north. C. Shrinkage of the natural range because of the limited number of habitats available in the north and the southern limit moving north D. Dispersal barriers prevent the colonization of potentially suitable habitats. E. Limited dispersal abilities prevent keeping up with rapidly changing conditions. F. Adaptation to the new conditions and expansion of the natural range (through evolutionary change). 27  Topic 14 Biosphere, ecology and conservation biology 14.3 – Biological and ecological interactions Interspecific interactions Species interactions influence the composition and dynamics of communities (short/long time-scales): à affect survival, reproduction, population sizes, evolutionary changes (morphology, physiology, behaviors). E.g. Competition, predation, herbivory, parasitism, mutualism, commensalism 29 Competition Competition occurs when two individuals of different species compete for a resource, limiting their growth and survival. Niche: all of the biotic and abiotic resources used by a species 2 barnacle species, Chthamalus stellatus and Ballanus balanoides have stratified distributions when they coexist. The removal of Balanus allows Chthamalus to occupy its fundamental niche à the realized niche is always smaller than the fundamental niche because of competition 30 Competition Competition occurs when two individuals of different species compete for a resource, limiting their growth and survival. Niche: all of the biotic and abiotic resources used by a species This can be as extreme as a competitive exclusion: à when populations of two similar species compete for the same limited resources à one population will use the resources more efficiently (reproductive advantage) à elimination of the other population. But resource partitioning (differentiation of ecological niches) can decrease competition and allow two species to coexist! Ex: 7 species of Anolis lizards coexist in the same habitat but occupy different niches. 31 Ecological change and evolutionary change Ecological interactions can drive evolutionary change E.g. predator-prey interactions, parasitism, mutualism, speciation, habitat loss Darwin finches: beak shape and size correlated with food acquisition Adaptation after a drought season: El Nino (1977), food became scarce Before drought Population size 751 à 90 birds = strong natural selection Most seeds available were large/hard-shelled à Favored large-beaked individuals through After drought increased relative survival From 1976 to 1977, average beak depth: 9.4à 10.2 mm 32 Trophic relationships Populations of intermediate trophic levels can be controlled by either: … the amount of food available in lower trophic levels (bottom-up control) … the presence of predators (top-down control) Ecological communities vary in the factors that controls the abundance and species richness (bottom-up or top-down). E.g. Sea star feeding on mussels. Experimental removal of Pisaster ochraceus à ↑ mussel population size à competitive exclusion of many invertebrates and algae species. Pisaster ochraceus is a keystone species: à has a large influence on species richness of the community relative to its abundance. 33 Commensalism Occurs when one individual from one species obtains a benefit while the individual from the other species is neither helped, nor harmed. Difficult to document because any close association affects both species, even slightly. E.g. Cattle egrets and buffalos. Cattle egrets benefit from insects flushed out of the grass by grazing buffalos. …but at times, buffalos benefit from the egrets removing ticks and ectoparasites from the herbivore’s body surface. E.g. Whales and barnacles: Barnacles filter food passively. … but whales may benefit from inflicting more damage while fighting (mutualism?) … or increased drag, slowing the whale (parasitism?) 34