Chapter 5 Species interactions, Ecological Succession, and Population Control How do species interact? Give some limited resources that organisms need in order to survive. Food, shelter, space, mate to reproduce, water, light air How might species interact to get these limited resources? Competition Have you ever competed with another organism to get what you wanted/needed? Interspecific competition is between different species. Intraspecific competition is between a single species. Competition Species need to compete because their niches overlap and they end up sharing the limited resources. When the word “share” is used here, it doesn’t mean equal sharing. Species like to reduce or avoid competition, so they resource partition. Competition Resource partitioning is a way for organisms to share a resource by using the resource at different times or using different parts of the resource. Predator/Prey interactions Predator is the hunter and feeds on the prey (the hunted) This interaction has a strong effect on population sizes. Predator/Prey interactions pg 134- 135 Give a way predators capture their prey. What are some ways prey avoid predators? Birds of prey (predators) and prey Google search ‘Birds of Prey’ – the Nature Conservancy has a great site Google search ‘bluebird, robin, sparrow’ Answer: 1. What differences do you notice regarding placement of the eyes in each group? 2. How might the difference in eye placement benefit each group of birds? What is mimicry? • Mimicry is the similarity of one species to another species which protects one or both organisms. Can be in appearance, behavior, sound, scent and even location. Who are the players? Mimics can be good tasting (easy targets) so they need to gain protection by looking like something bad tasting or dangerous. Models have a survival method that the mimic wants to duplicate. Some are dangerous or taste bad. Batesian Mimicry Form of mimicry when a non- harmful mimic species gains protection by looking like a noxious or dangerous model species. Example: Coral snake and Kingsnake Snakes Coral snakes The Scarlet Kingsnake looks almost EXACTLY like the Coral snake, but it is perfectly harmless! Mullerian Mimicry Both the mimic and the model are unpalatable (bad tasting) and both benefit. Example: Viceroy and Monarch butterflies Monarch versus Viceroy Take a look at these two butterflies. One is a Monarch and the other is the Viceroy both are very yucky to eat. If an animal eats the butterflies it will HATE it. The predator will stay away from ALL butterflies that are orange and black. Both benefit. Sea slug and Flatworm • Can you guess which one is a sea slug and which is the flatworm mimic? The sea slug gives off poisonous, smelly chemicals to discourage its predators. Why would the flatworm want to look like the sea slug? Snake or Caterpillar? Is it a snake or a caterpillar? The enemies of the Hawk Moth caterpillar don't know! So they avoid it-- just in case! Camouflage Butterfly wings or owl? Evolution At the population level, predation plays a role in natural selection. Predators kill the sick, weak, aged, and least-fit members of a prey population. Individuals with better defenses against predation tend to survive and leave more offspring with these adaptations. Coevolution When changes in the gene pool of one species lead to changes in the gene pool of another species Coevolution Example: Flowers compete for pollinators. The plants that produce flowers (with colors, shapes and scents specific to particular pollinators) that attract the most effective pollinators will set the most seed and have the most offspring. Parasitism The host is an organism that the parasite lives in or on to get what it needs. The parasite will not kill host (in most cases) since it would kill its food source. Example: tapeworms, mistletoe plants, fleas, ticks Mutualism Two species benefit by providing each with food, shelter, or another resource Example: pollinators and their plants Commensalism One species benefits and the other gets nothing out of the relationship Example: birds nesting in trees Create a chart with the relationships Relationship Species A Species B Competition Predation Parasitism Mutualism Commensalism Add in each box a +, -, or 0 for the relationship effects on each species. Succession There are many reasons for succession such as fires, volcanic eruptions, climate change, mass extinction or clearing of forests to plant crops. Ecological succession is the gradual change in type of species and number of species over time. Succession Two types: 1. Primary ecological succession- begins where there is no soil (land) or no bottom sediment (aquatic) Example: bare rock, cooled lava, parking lot Succession 2. Secondary ecological succession – ecosystem has been disturbed or destroyed, but soil/bottom sediment remains Example: abandoned farmland, burned forest, flooded land Is faster than primary succession because soil takes 100s to 1000s of years to make and release the nutrients needed for life. Succession It is an ecosystem service. It increases the diversity of species in an ecosystem, promotes population control, increases food web complexity which enhances energy flow and nutrient cycling. A climax community is what is reached at the end of succession. We have a deciduous forest climax community. What limits population growth? Population – a group of interbreeding individuals of the same species that live together in the same area and at the same time Change in population = (births + immigration) – (deaths + emigration) What limits population growth? Range of tolerance – a range variations in an organism’s physical environment under which it can survive What limits population growth? Limiting factor is an abiotic (nonliving) thing that limits the growth of a population. If it is a nutrient like phosphorus in water, then plants will deplete this factor first and limit plant growth. What do you think is the limiting factor in a desert ecosystem? What limits population growth? Limiting factors could include: -precipitation -space -temperature -predators/hunters -depth -disease -amount of sunlight -food amount -nutrient availability -acidity -seasons -salinity -competition -oxygen gas levels What limits population growth? Population density – is the number of individuals in a population found within a defined area or volume Density-dependent factors affects growth when the population density is high -parasites and diseases spread quickly -find mates easier What limits population growth? Density-independent factors affect population sizes no matter the population density -drought -climate change -flooding -hurricane/tornado/volcano eruption Exponential Growth In exponential growth, a large number of individuals is added to the population in each succeeding time period. Growth of a population Can a population exponentially grow forever in an ecosystem? NO!! A limiting factor will slow or stop the growth of a population. Carrying Capacity Carrying capacity is the largest population that an environment can support at any given time. A population may increase beyond this number but it cannot stay at this increased size. Carrying Capacity – Logistic Growth (S-shaped curve) Population Crash When a population uses up the resources by exceeding their carrying capacity and there is a sharp decline in the population size. Population Crash Reproductive Patterns Characteristics of r-selected species -short life span -produce many, usually small, offspring so a few will survive -parents provide little to no care -opportunist species have irregular boom and bust population sizes Examples: bacteria, insects, plant seeds Reproductive Patterns Characteristic of K-selected species -reproduce later in life -have few offspring -have long life spans -cared for by parents, herds -vulnerable to extinction Examples: large mammals, birds of prey, long-lived plants Survivorship Curves .