Biodiversity and species

1. Biodiversity and species Week six

2. The role of each species in an ecosystem • Ecological niche: each species has a distinct role to play in the ecosystems where it is found. It is a species way of life in a community and includes everything that affects its survival and production (such as water, kind of feed, space, sunlight, temperature etc it needs). It is its pattern of living and is different from its habitat. • Niche is used for classifying the species into: • Generalist species: species with a broad niche and ability to live in many different places, eat various foods, tolerate range of environmental conditions. (flies, cockroaches, mice, rats, raccoons, and human) • Specialist species: species that occupy narrow niches and able to live in only one type of habitat, eat a few types of food, and tolerate a narrow range of climatic and environmental conditions

3. Classification of species by using Niche • Niche classified in terms of species roles within ecosystems to five role and certain species may play one or more of these roles: • Native Species: are those that normally live and thrive in a particular ecosystem. • Nonnative Species: are those that migrate or deliberately or accidentally introduce into an ecosystem. They also called invasive, alien, or exotic species. • Indicator Species: provide early warnings of damage to community or an ecosystem such as trout for water quality, birds for environmental changes, butterflies for plant and habitat loss, amphibians for environmental condition and pollution and increase in UV and climate change and global warming, • Keystone Species: are the species that have a large effect on the types and abundances of other species in an ecosystem. (pollination or top predator) • Foundation Species: play a major role in shaping communities by creating and enhancing their habitats in ways that benefit others. (elephants for forest openings, Beavers making wetlands, birds draping seeds)

4. How do species interact • Five basic types of interaction between species for sharing limited resources such as food, light, shelter, and space: • Interspecific competition: رقابت دورن گونه ایoccurs when members of two or more species interact to gain access to the same limited resources • Predation: شکاریoccurs when a member of one species (predator) feeds directly on all or part of member of another species(prey) • Parasitism: طفیلیoccurs when one organism (parasite) feeds on the body of, or the energy used by, another organism (host), usually living on or in the host • Mutualism: همزیستیis an interaction that benefits both species by providing each one limited resources • Commensalism: همسفرگیis an interaction that benefits one species but has little, if any, effect on the other Conclusion: these interaction have significant effects on the resources use and population sizes of the species in an ecosystem.

5. Natural Selection and Reduction of Competition between Species • Some species develop adaptation that allow them to reduce or avoid competition with other species for resources • Resource partitioning is a way to realize it and occur when species competing for similar scarce resources evolve specialized traits that allow them to use shared resources at different time, in different ways, or different places populations S. A S. B A B niche overlap Resource Use

6. Limits of the growth of populations • No population can continue to grow indefinitely because of: • Limitation on resources and; • Competition among species for those resources • Population characteristics: • Distribution • Numbers • Age structure • Density • Population Dynamics: is a study of how population characteristics evolve in respond to environmental changes(such as temperature, presence of diseases and harmful chemicals, resource availability, in or out competing species)

7. Species population distribution or dispersionپراکندگی • Dispersion of a species in a habitat includes: • clumps or Patches گله ای یا لکه ای • Uniform dispersion: is for mentioning a fairly constant distance between individuals to have better access to scarce resources • Random dispersion :which are fairly rareپراکندگی تصادفی • The living world is mostly clumpy or patchy • Clumping happens because of: • Availability and concentration of resources that a species needs, in a certain places and environmental conditions • Moving in groups create better chance of encountering resources • living in groups protects some individuals from predators • Hunting in packs gives some predators a better chance of finding and catching prey • Grouping makes mating and caring for young easier

8. Population and Age Structure • Population’s Age Structure: is the proportions of individuals at various ages and usually divided to: • Pre-reproductive age • Reproductive stage • Past- reproduce- live stage Population change = (Births + Immigration) - (Deaths + Emigration) • Biotic potential:توان حیات: ظرفیت رشد جمعیت در شرایط ائده آل is the capacity for population growth under ideal conditions • Generally large species have low B.P. Such as elephants and small individuals have high B.P. such as bacteria.

9. Intrinsic rate of increase • Intrinsic rate of increase (r): نرخ رشد ذاتی یا طبیعیis the rate at which the Biotic potential of a species would grow if it had unlimited resources. • Population with high (r) has following characteristics: • Reproduce early in life; • Have short generation time; • Can reproduce many times; and • Have many offspring each time they reproduce. • There are always limits to Population Growth in nature. Limiting factors for growth: • Light and Space, Water and Nutrients, • Many competitors, predators, and infection disease.

10. منحنی رشد منطقی Logistic Growth Curve • Environmental resistance: is the combination of all factors that act to limit the growth of population. • مقاومت محیطی: ترکیبی از تمامی عوامل محدود کننده رشد است • Carrying Capacity: توان تحملthe maximum population of a given species that a particular habitat can sustain indefinitely without being degraded. • توان تحمل: حداکثرجمعیت یک گونه در داخل یک زیستگاه در شرائط پایداری بلند مدت و بدون تخریب آن است. • J – Curve: rapid exponential population growth. • S – Curve: a plot of number of individuals against time yields a sigmoid or S – Shaped curve. • Logistic Growth Curve: It involves rapid exponential population growth followed by a steady decrease in population growth until the population size levels off. • این منحنی شامل رشد سریع نمایی جمعیت گونه وسپس کاهش تدریجی رشد جمعیت تا دستیابی به سطح تعادل جمعیتی است.

11. Interaction of Biotic Potential and Environmental Resistance

12. Species Reproductive Patterns • r- selected species: حشرات، جلبکها، گیاهان تکساله، باکتریها، قورباغه ها • Many, small, little or no parents protection or care, mass mortality of offspring with sort time life • They are opportunists, reproduce rapidly by favourable environmental conditions • Irregular and unsustain boom and bust cycles in population size • k- selected species:پستانداران بزرگ مثل فیلها، والها، انسانها،گیاهان چند ساله • Reproduce late in life, small number of offspring, born fairly large, mature slowly, cared by 1 or both parents, living in groups • Their population follow a logistic growth curve, population size is near to carrying capacity (k) • Normal species: most of organisms reproductive pattern is in between

13. Affects on population size • Genetic diversity: • کاهش تنوع ژنتیکی در داخل یک گله منجر به کاهش جمعیت آن گونه میگردد از طریق: • Founder effect اثر بنیان گذار • Demographic bottleneck اثر جمعیت نجات یافته از حوادث • Genetic driftاثرغلبه ژنیتیکی (یک گروه با توان تولید نسل بیشتر در داخل یک گله) • Inbreeding اثر فامیلی (تولید نسل در داخل یک فامیل) • Island biogeographyاثر منزوی شدن یک گروه • Population density:

14. Types of population fluctuation (change) in Nature • در طبیهت چهار الگوی اصلی تحول جمعیتی یافت میگردد • Stable: population size fluctuate slightly above or below carrying capacity • Species living in undisturbed areas with stable annual average temperature • Irruptive: population exploded to high pick and then crash • Many of r-selected species • Depends of seasonal weather and nutrient availability • Cyclic fluctuation: جهش جمعیتی در یک دوره زمانی مشخص • Lemmings in 3-4 yearsموش صحرایی قطبی, lynxسیاهگوش and snowshoe hare خرگوش قطبی in every 10 years • irregular change with no recurring pattern

15. Theory of ecological succession and Natural ecological restoration • The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession. • ecological succession: the gradual change in species composition in an area, while some species colonize the area and their population increase and population of other species decrease or disappear. • Stat by arriving colonizing or pioneer species and environmental changes • Primary succession: the gradual establishment of biotic communities in lifeless areas with no soil or bottom sediment • Secondary succession: a series of communities and ecosystems with different species develop in an area contain soil (terrestrial) or bottom sediment (aquatic) • Succession doesn’t follow a predictable path (no balance of nature) • Living systems are sustained through constant change

16. Nature’s four scientific principals of sustainability • Reliance on solar Energy: the sun warms the planet and supports photosynthesis used by plants to provide food for themselves and for us and most other animals. • Short for Biological diversity: the astounding variety of different organisms, the genes they contain, the ecosystem in which they exist, and natural services they provide have yielded countless ways for life to adapt to changing environmental conditions throughout the earth’s history. • Population Control: competition for limited resources among different species places a limit on how much their populations can grow. • Nutrient Cycling: natural processes recycle chemicals that flora and fauna need to stay alive and reproduce.

17. Usage of Four Scientific Principles of sustainability • To design of our economic and social systems; • To design our individual lifestyles; • To help slow human population growth; • To sharply reduce poverty; • To curb unsustainable forms of resource use and save natural capital; • Create a better world for ourselves, our children, and future generations