General Biology 1 Ecology Part 1 Fall 2024 PDF

General Biology 1 Fall 2024 Ecology – part 1 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  Book Study guide: Topic References (1...

General Biology 1 Fall 2024 Ecology – part 1 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  Book Study guide: Topic References (13th Ed) Describe key elements of an environment. Relate the concept of homeostasis Section 54.1, pages 1216-1218 to response to an environment. Define the term population and provide the characteristics that can be used to Section 54.2: pages 1218-1221. define and study populations: size, density, dispersion, age structure & sex Section 54.3, pages 1222-1224. ratio. Section 54.5, pages 1227-1228, Define population growth and the factors involved in determining or predicting Figure 54.16 population changes. Section 54.6 pages 1229-1231. Section 54.3, page 1223-1224, Identify and interpret a survivorship curve. Figures 54.10 & 54.11 Section 54.3, page 1223, Table Understand the uses of a life table for predicting population growth. 54.2 Section 54.7, page 1233, Figure. Interpret population pyramids. 54.26 Relate the age structure and population size to the life history of the species Section 54.4, pages 1224- 1226. and reproductive patterns. Define population growth in terms of exponential growth and logistic growth Section 54.5, Figures 54.16, 54.17 models. & 54.18 Define carrying capacity and differentiate between K-selected and r-selected Section 54.6, page 1227 & 1231, life histories. Table 54.3 Differentiate between density dependent and density independent factors Section 54.6, pages 1129-1231; influencing population growth. Explain population cycles. Figures: 54.19 to 54.23  Ecology Ecology Definition: Ecology is the study of how organisms relate to one another and to their environments. The nature of the physical environment in large measure determines which organisms live in a particular climate or region. Key elements of the environment include: Environmental factors: Temperature Water Sunlight Soil  Ecology Responses to Environmental Changes Homeostasis: Individual must maintain a steady-state internal environment regardless of external environment. Physical Chemical Set point factor Time Cells within living organisms can only function optimally in a narrow range of physical (ex.: temperature) and chemical (ex.: salt, sugar, etc.) values. Conformer: Certain animals and plants are known as conformers because they conform to the environment in which they find themselves, their bodies adopting the temperature, salinity, and other physical aspects of their surroundings.  Ecology Responses to Environmental Changes There are three ways that an organism can respond to environmental change. 1) Physiological responses 2) Morphological adaptation 3) Behavioral responses  Ecology Responses to Environmental Changes Temperature: Most organisms are adapted to live within a relatively narrow range of temperatures. 1) Physiological responses Set point Temperature 37˚C Time Homeostasis  Ecology Responses to Environmental Changes Temperature: Most organisms are adapted to live within a relatively narrow range of temperatures. 1) Physiological responses Certain species of frog will produce antifreeze, high concentration of glucose, to prevent the formation of ice crystals which would damage their cells. This will prevent the frog's vital organs from freezing. A partially frozen frog will stop breathing, and its heart will stop beating. Conformer Ectotherms: Animals such as reptiles, fish, or amphibians, whose body temperature is regulated by their behavior or by their surroundings.  Ecology Responses to Environmental Changes Temperature: Most organisms are adapted to live within a relatively narrow range of temperatures. 2) Morphological adaptation Endotherms, animal that can generate its own heat, have adaptations that minimize energy expenditure. Homeostasis For example: Thick fur coats during the winter  Ecology Responses to Environmental Changes Temperature: Most organisms are adapted to live within a relatively narrow range of temperatures. 3) Behavioral responses Many animals deal with variation in the environment by moving from one patch of habitat to another, avoiding areas that are unsuitable. Ectotherm: Animals such as reptiles, fish, or amphibians, whose body temperature is regulated by their behavior or by their surroundings. For example, in orange in the graph a tropical lizard use behavior, sunbathing, to keep warm. While in green, lizard does not have the opportunity to regulate its body temperature through behavioral means. Thus, it becomes a conformer and adopts the temperature of its surroundings.  Ecology Responses to Environmental Changes Water: All organisms require water. On land, water is often scarce, so patterns of rainfall have a major influence on life. Morphological adaptation Behavioral responses Beetle collects water by holding its abdomen up Camel can withstand long on a dune crest to gather periods of time without any condense water. external source of water.  Ecology Responses to Environmental Changes Water: All organisms require water. On land, water is often scarce, so patterns of rainfall have a major influence on life. Precipitation varies according to geographical location  Ecology Responses to Environmental Changes Sunlight: Almost all ecosystems rely on energy captured by photosynthesis. The availability of sunlight influences the amount of life an ecosystem can support. Except in underwater thermal vent where life thrive on Earth thermal energy and dissolve elements.  Ecology Responses to Environmental Changes Sunlight: Almost all ecosystems rely on energy captured by photosynthesis. The availability of sunlight influences the amount of life an ecosystem can support. Deciduous trees shed their leaves in Fall, which is a strategy to deal with the short amount of sunlight in Winter.  Ecology Responses to Environmental Changes Soil: The physical consistency, pH and mineral composition of the soil often severely limit terrestrial plant growth, particularly the availability of nitrogen and phosphorus. High temperature, salts and pH limits the growth of life in Yellowstone Geyser. Only extremophile can live in those conditions.  Ecology Responses to Environmental Changes Natural selection leads to evolutionary adaptation to environmental conditions When you compare closely related species that live in different environments you can see the adaptation strategy. Allen’s rule of reduced surface area: Mammals from colder climates have shorter ears and limbs to limit heat loss. Fennec fox (Vulpes zerda) Sahara desert Arctic fox (Vulpes lagopus) Arctic tundra  Ecology Responses to Environmental Changes Natural selection leads to evolutionary adaptation to environmental conditions Natural selection can also be detected by comparing populations of the same species that live in different environments. For example, most Tibetan highlanders have two mutations in a gene related to oxygen uptake, but few individuals in nearby lowland populations have these mutations. These results suggest that natural selection has driven these mutations to high frequency in very little time, it’s only been a few thousand years since the Tibetans colonized the Himalayas.  Ecology Population Definition: groups of individuals of the same species that live together in the same space and time. 3 characteristics of population ecology: 1) Population range 2) Population spacing 3) Metapopulation  Ecology Population 1) Population range: area in which a population occurs. Polar bears are well adapted for the Arctic but you won’t find them in the tropics. Map of a polar bear range using GPS  Ecology Population 1) Population range: area in which a population occurs. The Devil’s hole pupfish have a very narrow distribution range. They only live in one water- filled cavern in the US state of Nevada. Due to their narrow distribution range they are extremely in danger of becoming extinct. In 1972 the population counts was around 550, in 2013 was only 35, but it increased to 136 by 2019.  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time. 1) Environmental change Example: The environment changed after the glaciers retreated. Plant and animal population expanded northward.  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time. 1) Environmental change Shifts in attitudinal distributions of trees in the mountains of southwestern North America. During the glacial period conditions were cooler than they are now. As the climate warmed, tree that need colder temperatures shifted their range upward in altitude so that they continue to live in the colder climatic conditions.  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time 2) Colonisation of new territory Example of the cattle egret The cattle egret expanded its range across an ocean, from Africa to South America, probably on strong winds. The egret continues to expand its range northward in America.  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time 2) Colonisation of new territory Example of the human effect: Coyotes range expansion By altering the environment, humans have allowed some species to expand their ranges. Coyotes began expanding their range in 1900s. This was likely aided by an expansion of human agriculture, forest fragmentation, and hybridization with other species (wolf and dog).  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time 3) Dispersal Mechanisms Example seed dispersal: Seed can be disperse by the wind. Seed can adhere to the fur of animal. Seed in fleshy fruit can eaten and poop elsewhere.  Ecology Population 1) Population range expansion and contraction − Population ranges can change through time 3) Dispersal Mechanisms Thistle dispersal Coconut dispersal  Ecology Clumped Population 2) Population spacing patterns − Individuals in populations exhibit different spacing patterns. Uniform 1) Clumped spacing 2) Uniform spacing Random 3) Random spacing  Ecology Population 2) Population spacing patterns − Individuals in populations exhibit different spacing patterns 1) Clumped spacing Social interactions can lead to clumped distributions. Many species live and move around in large groups. Advantages: increased awareness of and defense against predators, decreased energy cost of moving through air and water. May also represent uneven distribution of resources; like food, which is common in nature.  Ecology Population 2) Population spacing patterns − Individuals in populations exhibit different spacing patterns 2) Uniform spacing Uniform spacing within a population may often, but does not always, result from competition for resources. (example of trees competing for light in a forest). In animals, uniform spacing often results from behavioral interactions (example of Royal Penguin competing for space to incubate their egg).  Ecology Population 2) Population spacing patterns − Individuals in populations exhibit different spacing patterns 3) Random spacing Individuals within populations do not interact strongly with one another. Rare, can be difficult to determine between random or largely clumpy. Example: a field of dandelions  Ecology Population 3) Metapopulation Metapopulation comprises distinct populations that may exchange members. Metapopulations usually occur in areas in which suitable habitat is patchily distributed and is separated by intervening stretches of unsuitable habitat.  Ecology Population 3) Metapopulation Source-sink metapopulations Areas in which some habitats are suitable for long-term population maintenance, but others are not. dispersers Dispersal: Populations center (source) send dispersers to surrounding areas (sink). Small populations send fewer dispersers and receive more migrant. dispersers Individual populations may become extinct (disease, environmental dispersers disaster, lost of genetic variation).  Ecology Population 3) Metapopulation Metapopulations impact on range Continuous colonization of empty patches prevents long-term extinction. In source–sink metapopulations, the species occupies a larger area than it otherwise might. dispersers That’s the idea behind Elon Musk colonization of Mars. To be a multiplanetary species and prevent our extinction.  Ecology Population 3) Metapopulation Study of Glanville fritillary butterfly at 1600 meadows in southwestern Finland. 200 populations became extinct, but 114 empty meadows were colonized. Local population's extinction, is due to small population size, low resource availability (flowers), and lack of genetic variation within the population. None of the populations is large enough to survive for long on its own, thus this butterfly need the continued existence of a metapopulation network, which new populations are continually created and existing populations are supplemented by immigrants.  Ecology Population demography and dynamics Births Deaths Births and immigration add individuals to Deaths and emigration a population remove individuals from a population Immigration Emigration  Ecology Population demography and dynamics Demography: it’s the quantitative study of populations, it examines how a population changes size over time. Factors that Change a Populations Size 1) Birth Rate (b): the number of live births per time 2) Death Rate (d): the number of deaths per time 3) Immigration (i): the number moving in the population per time 4) Emigration (e): the number leaving the population per time Rate of population increase: r = (b-d) + (i-e)  Ecology Population demography and dynamics  Ecology Population demography and dynamics Population growth can be influenced by the population’s sex ratio − Number of births directly related to number of females. − The number of male usually don’t affect the birth rate, since male can mate with several female. − With the exception of monogamous species, where the number of male is important.  Ecology Population demography and dynamics Generation times: average interval between birth of an individual and birth of its offspring. − Populations with short generations can increase in size more quickly than populations with long generations. You have about 100 mouses generation for each elephant generation.  Ecology Population demography and dynamics Deer Average lifespan in wild is 10 to 13 years. Deer give birth to 1-3 young/year. The deer will produce a maximum of 39 offspring in 13 years. Mosquito Female mosquito’s live 14 – 21 days. Lay ~300 eggs in a lifetime.  Ecology Population demography and dynamics Generation times is positively correlated to the body size. Small size does not always mean short generation time. Newts, for example, are smaller than mice, but have considerably longer generation times. Newts  Ecology Population demography and dynamics Population pyramids Canada 2022 Age structure: Determined by the numbers of individuals in different age groups. Baby boomers Age Children's on Baby Cohort: boomers A group of individuals of the same age (born in the same period). Population  Ecology Population demography and dynamics The probability that an individual will reproduce or die varies through its life span. Thus every cohort has a birth rate (fecundity rate) and a death rate (mortality rate). Each Cohort has: - Fecundity rate: defined as the number of offspring produced according to time. - Mortality rate: number of individuals that die in that period. Births Deaths  Ecology Population demography and dynamics The relative number of individuals in each cohort defines a population's age structure. Population pyramids Because different cohorts have different fecundity and death rates, age structure has a critical influence on a population's growth.  Ecology Population demography and dynamics Japan Population pyramids Populations with a large proportion of young tend to grow rapidly because an increasing proportion of their individuals are at reproductive age (ex.: Japan in 1950).  Ecology Population demography and dynamics Japan Population pyramids Populations with a large proportion of older individual tend to decrease, since only a small fraction of individuals are at reproductive age (ex.: Japan in 2023).  Ecology Population demography and dynamics Japan Population pyramids Populations with a large proportion of young tend to grow rapidly because an increasing proportion of their individuals are at reproductive age (ex.: Japan in 1950). Populations with a large proportion of older individual tend to decrease, since only a small fraction of individuals are at reproductive age (ex.: Japan in 2023).  Ecology Population Pyramid Bar graph displaying the number of people in each age category Kenya’s population could double in less than 35 years, whereas Sweden’s will remain stable Reproductive age  Ecology Population Pyramid During the U.S. “baby boom” (1946 – 1964) 75 million babies were born. Birth rates declined during the 1960s, but when baby boomers became parents, they generated a “baby boom echo.”  Ecology Population Pyramid Population pyramid shape and prediction of demographic trends Triangular pyramid Rectangular pyramid Inverted triangles pyramid Characteristic of a country with Characteristic of countries rapid future growth because most whose populations are Characteristic of populations of its population has not yet stable, neither growing nor that are shrinking, usually as entered the childbearing years. shrinking. a result of sharply declining Japan birth rates. 1950 2010 2050