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Queen's University
BIOL 302
Laurene M Ratcliffe

What are the ecological consequences of variable photosynthetic strategies in plants? 3 ways to photosynthesize C23 plants (ancestral pathway) Most widespread (97% land plant species) More abundant towards pole and up mountains (cooler temperatures) Responsible for 75% of plant growth C3 plants do BEST: • Where CO2 is abundant (have low affinity for CO2) • Under moderate temperature (20-25°C) and light levels (1/4-1/3 full sunlight) • With abundant water (b/c lose water quickly via transpiration C3 Photosynthesize via the Calvin Cycle Just know the application of the cycle M & C Fig 7.4 C3 plants do best… Where CO2 is abundant (have low affinity for CO2) Under moderate temperature (20-25 degrees Celsius) and light levels (1/4 – 1/3 full sunlight) With abundant water (because lose water quickly via transpiration) C4 Plants Have evolved from C3 plants (discover 1965!) Have C3 pathway PLUS second pathway Comprise only 3% of plant species (about 7500) More abundant towards equator (Warm temperatures) – grasses, sedges Responsible for 25% plant growth BUT many key food species Difference in C3 and C4 chlorophyll starts with their leaf anatomy (look at diagrams of them) C4 plants are designed to pick up CO2 (high affinity) – do not need to open stoma as often as C3 plants C4 plants do best: Under hot temperatures (optimum at 30-35 degrees Celsius) and high light levels (full sunlight) Where CO2 is limited (high affinity for CO2) Can tolerate lower water levels as low transpiration When comparing to C3 plants, C4 plants: Are more efficient @ low CO2 Don’t reach full photosynthetic capacity (saturation) even at full sunlight Produce more sugars and starches per unit leaf area C4 plants dominate in warmer latitudes CAM photosynthesis =Crassuleacean Acid Metabolism (rarest form!) 2 stages Fix Carbon at night: CO2 = malate Complete photosynthesis next day (optimum at 35 degrees C) Energy and Nutrients (Chapter 7) Chemical autotrophs are found in extreme environments (i.e. bottom of ocean) – fig 7.15 Chemoautotrophic sulfur-oxidizing bacteria provide nutrients – oxidize hydrogen sulfide and yields energy Chemical Autotrophy: Nitrifying Bacteria – M & C Fig 7.16 What do Carbon: Nitrogen Ratios tell use about heterotrophs? Heterotrophs (animals, fungi, bacteria) are large weight; low C: N ratio organisms Fairly high levels of nitrogen in tissues Plant have high C: N ratio. Why? Cellulose and other rigid structures have a major impact to this. Always short of Nitrogen; rich in carbon Nutrient challenges facing herbivores High C: N ratios in plants foods Inedible tissues (cellulose, lignin) Adaptations: Bulk feeders, ruminants Substantial individual variation in diets of carnivores: extremely variable diet Photosynthetic response curve (fig 7.18) Food density and animal functional response (Fig 7.21) Type 1: linear increase in food uptake with prey density until maximum rate Type 2: initially linear increase, then slowed rate of increase before leveling off Type 3: S-shaped: slow rate of increase initially, then faster until maximum level Optimal time to feed in a patch: the marginal value theorem (Fig 7.24a) Natural selection acts in a way to maximizes ones fitness Brain and hormone production has an effect on fitness Age at which you first reproduce Number of offspring you have (how often or just one batch and die) Allocate energy to certain aspects during reproduction Schedule of ones reproductive patter is called life history Life history includes- responses to environment, all the behaviour and physiological adaptation or organisms. Organisms general body plan Ideal organism should-reproduce right after birth, produce many well adaptive young and live for a long time, provides unlimited parental care. But limits to time and energy force trade offs Coconut palms are well-lived have small amounts of offspring because there is a lot of energy going into being produced Make the best use of your time energy and resources. Selection acts on these strategic decisions The life plan that results =life history (usually species specific) Outline A) Life history traits are shaped by selection B) Trade offs: survival and reproductive effort C) How genes and environment shape life history D) From r and k to “life history cubes” Why do birds in the tropics lay fewer eggs than close relatives further north? Latitude (in tropics stuck with 12-hour day length The number of eggs laid is ultimately limited by the number of offspring parents can feed Maximize difference between the benefit and the cost Clutch is # of eggs in a nest Life history-traits influence fitness, open to selection, makes testable predictions Conflict between the sexes explains why ‘11’ egg is the optimal clutch size in blue tits Life history results from selection to optimize fitness vie strategic decisions about survival and reproduction Life histories are limited by the species history (phylogeny) Body size Mode of thermoregulation Mode of reproduction B) Physiological =growth vs. reproduction or survival Larger the female the more offspring she will have The biggest the eggs the smaller the gene flow Reproductive=reproduction vs. survival, offspring vs. fecundity, age of first reproduction vs. mortality Huge variation in plant seed sizes across species Negative relationship between seed mass and seed number Larger seeds=greater recruitment Smaller seed=better germination in disturbed environments If reproduction trades off against survival why variation in senescence? Senescence=gradual decline, common Difficult to detect Not just wear and tear because longevity varies across species of similar size and physiology Mice live 3-5 years bats 10-20 years Key variable=pattern of adult survival If low adult survival, selection should favours early faster senescence (mice) If high senescence should start later and be more gradual (bats) Mortality rates should be key to age at first reproduction (fig 9.10) Distribution and abundance of populations and species Key factors affecting abundance is the locations populations can make a living in -Social consequences: one child policy Distribution and abundance Range limits Dispersion patterns Metapopulations Predictive patterns Are fundamental population parameters, determined by population dynamics Distribution: size, shape and location area occupied Density=number of individuals per unit area, or absolute density *Ecologists measure relative density=number of individuals per unit area suitable habitat Estimating abundance is challenging -Diatoms 5mil/m3 -Trees 500/ha -Humans (Canada) 2/km2 Estimating abundance -B-birth rate -I – immigration -D-death rate -E-emigration -When density changes due to what parameter Challenges: wide range of densities, size and mobility of organisms Measuring absolute density -Total counts (censes, aerial, colony snapshots) Sample counts Compute recapture, quadrats Lincoln Peterson Mark recapture (275-278) Assumptions of mark recapture methods -Closed pop b/w time of marking and checking -All animals are equally likely to be captured -Markings don’t disappear or fall off Do we really know the area over which density is being estimated? Still a common method for measuring Absolute Density Measuring relative density -Pellet counts, artifacts, questionnaires, and bait -Citizen science Why do species have range limits? -Physical environment limits geographic distribution of a species; at the edges of a species niche, the metabolic costs of dealing with environmental stressors become to great. (Some leave the area to survive) Tiger beetle lives at higher latitude and elevations than most other tiger beetle species in North America. As long as a microclimate is available they are able to survive in different climates (fig 10.3) Individuals often have narrow tolerances -Despite large geographic separation of populations, physiological tolerance are vey similar (fig10.4) Example 2 barnacles along moisture gradient -Chthamalus (top of tidal level, often dried out) and Balanus (lower level needs moisture most of the time) have evolved different degrees of resistance to drying -Differ in distribution along Scotland coast Fig 10.7 -found in warm weather with calm seas, there was a lot of mortality in the -1954/55 –looked at remaining living chthamalus with bal removed or not -With removed they grew Climate-mediated range shifts -May increase extinction risk -Previous studies show individual species have shifted to higher latitudes and elevation -Are greater shifts occurring in regions with greater warming? -Does this occur across taxonomic groups? Spatial distributions within populations -Though no species occurs everywhere, we don’t really know the actual area occupied by most species, because detailed mapping hasn’t been done -Most species geographic rage is described on -Small scale: distance of no more than a few hundred meters over which there is little environment change significant to organism under study -Large scale: area over which substantial environment change. Eg patterns among mountain slope or entire continent (actual scale depends on study question and money) (fig 10.8) -Random =mosquitoes -Regular=humans Clumped= trees, resource variation Ethical Review and Regulatory Oversight of the Use of Animals in Research and Teaching Regulatory Oversight - Animals for Research Act – provincial - RRO 1190 Regulation 24 research facilities and supply facilities Enforced by OMAF Annual unannounced facility inspections - Canadian Council on Animal Care Establish guidelines and policies and conduct assessment visits at least every 3 years Participants that have successfully completed the assessment receive a certificate of good animal practice Animal Care and Use Committee - Review and approval of all proposals to use animals Proposal has been reviewed for scientific merit Compliance with accepted ethical standards each protocol reviewed annually - Authority Halt any study that deviates from the approved protocol Animals are found to be suffering excessive pain or distress that cannot be relieved - Ensuring standards for animal facilities and care Facility standards and the care of the animals are in accordance with the CCAC guidelines - Prevention & relief of pain & distress & ensuring adequate veterinary care - Ensure training & skills of all persons working with animals used in science - Membership of the ACC Scientists and/or teachers experienced in animal care and use Veterinarian(s) experienced in animal care and use An institutional member whose normal activities do not involve animals At least one person representing community interests and concerns who does not have any links with the institution or with animal use for research, teaching or testing Technical staff involved in animal care and use Student representation in academic institutions Animal facility managers The Three R's - Replacement – methods, which avoid or replace the use of animals in an area where animals would otherwise have been used - Reduction - refers to any strategy that will result in fewer animals being used with no loss of useful information - Refinement - modification of husbandry or experimental procedures to minimize pain and distress Key Points When Planning a Study Animal safety should be highest priority Knowledge of a study species Inclusion of a pilot study when necessary Use of the least invasive practice possible Minimization of disturbance to animals and habitat Measures to prevent detrimental effects on the population Maximize information obtained and reduce impact on individual Know and minimize causes of stress or discomfort; a distressed animal provides poor data Capture Knowledge of species, molt behaviour, time of day, minimizing stress and injury, correct mesh size, no sharp edges, safe and easy to use, non-destructive to vegetation, evaluation of trapping method and planned endpoints, minimize by-catch Health Evaluation - Aspects to consider Respiration rate Feather condition Messy vent Pectoral muscle mass Cardiac function, capture myopathy Marking - All marking requires a capture and banding permit - Considerations for choosing a marking method: Species biology, ecology and behaviour Purpose of the study – individual or cohort marking Coordination with other studies Length of research Possibility of pain - Potential for injury and/or pain if improperly done Animal Trends 1975-2009 - A graph comparing fish, mice, rats and all categories Number of animals used vs. year - Second graph comparing cats, dogs and non-human primates Number of animals used vs. year Wildlife Use - Graph comparing birds with total wildlife (not including fish) - Graph – salamanders, toads, snakes and turtles Categories of Invasiveness - CCAC Categories of Invasiveness Category a – invertebrates or other live isolates Category b – little/no discomfort or stress Category c – minor stress/pain Category d – moderate to severe distress/discomfort Category e – major distress/discomfort Purpose of Animal Use PAU0 – breeding colony/stock PAU1 – studies of a fundamental nature PAU2 – medical purposes PAU3 – regulatory testing PAU4 – development of products The Distribution and Abundance of Populations / Species cont'd Distribution of individuals over arger scales -Reveals sig environmental variation -On scale, individuals are usually clumped  eg. Bird pop across north America “xmas bird counts (CBC) (American Crow) vs. (fish crow)  Started in 1900 with 27 observers sampling 26 localities (2 in Canada)  In 2008, 59813 observers in 2124 localities (361 in Canada)  Provides unique, extensive dataset on distributions of birds across NA Main areas are near urban or farms where during the winter food can be found. (American Crow) Where fish are found (Fish crows) Mainly In warmer regions and are very susceptible to blow outs (oil spill, natural disasters etc.) -Clumping occurs during breeding and xmas time (BBS) Relation b/w distribution and abundance -What does the distribution of a range size across species tell us?  Most species have very small range sizes  “Hollow curve” plot  Most species have evolved quite restricted ranges (food, salinity, temperature, other organisms are all restricting factors) -Are there global patterns in range size?  Yes  Productivity  Geographic range size decreases moving from the poles towards the equator (rapaports rule)  Climatic variability  Glaciation history  Lower competition in polar communities -Are species with large geographic ranges any more or less abundant than species with small geographic ranges?  Species abundant locally often have large ranges  It’s a conundrum nobody knows why  Positively correlated  Species that are abundant where they occur and are also generally widespread, rare species localized are at risk?  Hanski’s Rule  Why? : Artifact of sampling? ecological specialization?, local population model? If species declines in abundance, does its range become smaller? Yes and a no Metapopulations -Made up of a group of subpopulations living on patches of habitat connected by an exchange of individuals (Human activities such as logging lead to habitat fragmentation and can change population structure)  Affect: species abundance, gene flow between sub-populations, extinction/ re-colonization probabilities  Sub-populations at greatest risk, smaller, on smaller patches Rocky mountain Parnassian butterfly Extends from northern New Mexico to southwest Alaska  Host plant of caterpillars is Sedum found in Alpine meadows  Population size varies with meadow size, meadows getting smaller (more isolated) (fire suppression makes meadows smaller  Butterflies are more likely to leave small populations and disperse to larger populations Organism size and population density -As an organism gets bigger their density declines -But trophic relations affect these patterns too. -Same patterns across wide array of animal taxa Interesting differences among taxa, eg invets vs verts Plant population density decreases with increasing plant size across a wide range of plant growth forms -Underlying processes very different -Tree seedlings can live at high densities, but as they grow density declines progressively until mature trees are at low densities =self-thinning. Predicting patterns Rapaport’s and Hanski’s Rules Short hand model (are good dispersers) Can we predict commonness and rarity? -Yes these are determined by 3 factors:  Geographic range – wide vs. restricted  Habitat tolerance – broad vs. narrow  Local population size – large vs. small Rarity due to slow reproduction Wide range, broad habitat tolerance, small local populations  eg. Peregrine falcon (driven to brink of extinction by ddt in environment, saved by ban of ddt and captive breeding programs)  eg. Tiger (many small local populations driven to extinction by hunting, now only series of small fragmented populations) Wide range, narrow habitat tolerance, large populations  eg. Passenger pigeon (nested in large aggregations in virgin forests, logging of forests and hunting combined led to decline and last individual died in captivity in 1914  eg. Harelip sucker (common fish found in extremes in the US restricted to large pools with rocky bottoms clear streamwaters 15-30 cm) habitat eliminated by silting of rivers and erosion following deforestation collected in 1893 Extreme rarity, restricted range, narrow habitat tolerance small populations  eg. California condor, mountain gorilla, giant panda  Many island species have these attributes: of 171 bird species know to have become extinct since 1600, 155 were restricted to islands  Extreme rarity places species at highest risk of extinction Outline What survival, age and sex ratios tell us about population past and future Patterns of survival: life tables and curves Age distribution and population dynamics Operational sex rations: why rarely 1:1 Dispersal: causes and consequences for population density Population structure -Can be defined by number of factors  eg. Patterns of mortality, age distributions, sex ratios, dispersal In seminal work on dall sheep populations, Adolph Murie showed that mortality due to wolf predators mostly occurred in very young and very old individuals Patterns of survival Pattern of survival and mortality is fundamental to understand population structure  Survivorship curve: summarizes pattern of survival in a populations  Life tables ‘bookkeeping’ device tracts births, survivorship and deaths in population. 3 ways to estimate survival  COHORT life table (plant populations, follow babies born in a particular year) Identify everyone born at the same time, keep records from birth to death  STATIC life table (snap shot or cross section of a moment in time) Record age at death of large number of individuals over narrow window in time, called static because assumes the pop parameters are stationary. Requires accurate estimate of age at death (use tree rings, growth rings in sheep horns, etc.) Easier to implement Less accurate Widely used  MEASURE AGE DISTRIBUTiON Estimate how many individuals in each class are in the population. Eg seining fish at QUBS Calculated difference in the proportion of the individuals in each age class, assume this is equal to survival This also produces a static life table Common method but less accurate Individuals may disappear rather than die Population is changing (BIDE) not in equilibrium. Type 1 survival: high survival among young  Rotifers, flox  Humans Type II Survival: constant rate (equal chance of mortality at every age)  Water snakes at CUBES, white crowned sparrow  Songbirds Type III survival: high mortality of young (constant rate of survival)  Desert shrub, cleome droserifolia  Oysters Age distributions How many individuals are in each group in populations? Also called age structure Can reveal important aspects of population dynamics • Can be used to calculate life tables Humans are type one growth Italy =zero growth Mice –stable age distribution (fast majority are very young) Figure 11.9 abundance of young trees means sufficient reproduction to replace oldest individuals as they die 11.10 populations dominated by older individuals No successful reproduction at this site for over 10 years -> In the past when this was a natural site, the river flooded seasonally ->Wipes out existing vegetation, very soggy ground good for cottonwood seedlings Sex ratios also affect pop structure -Because females drive growth rate Most primary sex ratios at birth are close to 1:1-- why? Why so many males -Primary sex ratio vs. operational sex ratio (OSR): in humans, birth sex ratios slightly male biased (1.07:1), 1:1 at early adulthood, than steadily more female-biased (0.78:1) Fisher why the operational sex ratio is 1:1 Selection always favours parents investing equally in sons and daughters -But the benefit (relative fitness) of producing a son or a daughter depends on the relative frequency of males and females in a population (frequency dependent selection) Example-benefit of producing a son decreases as a population becomes male biased What does equally mean?  If sons and daughters are equally costly to rear (time energy, risk) then produce equal numbers of sons and daughters  But if one sex costs more to rear (red deer sons) then a parent should invest equal energy in producing sons and daughter (could be fewer sons than daughters)  Selection acts on parents to have the sex ratio of offspring that maximizes the number of grandchildren Sex determining mechanisms are highly variable  Genetic (XX/XY, ZZ/Zw)  Or environmental (conditions during early development, temperature, density)  Females may skew sex ratios in response to paternal quality (mechanisms unclear, differential fertilization success by sperm, differential implementation, embryo resorption)  Whiptail lizards (no males)  Biased ratios can arise via.  Differential mortality (can cause sex ratios to vary among age classes)  Differential costs of offspring (birth weight, lactation demands)  Differential probability of mating (skewed OSR due to intra-sexual competition)  Differential dispersal behaviour Dispersal  Affects –population distribution and differentiation  Natal dispersal: from hatch/birth to first breeding site (often sex-biased)  Adult dispersal: can also occur=movement out of local population Invasive populations are fast dispersers  Spectacular examples  Zebra mussels (great lakes), cane toads, mountain pine beetle (BC, AB) Africanized honey bees
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