Download Biodiversity week 5

Biodiversity
Week Five
Biodiversity makes life Sustainable
 Life depend on energy from sun (solar capital) and on natural
resources and natural services (natural capital) provided be
the Earth and its biodiversity.
 Living sustainably means living off the earth’s natural income
without depleting or degrading the natural capital that
supplies it.
Natural Capital of Biodiversity and its
ecological services
 Supplying food, wood, fibers, energy and medicines
 Preserving the quality of the air and water
 Maintaining the fertility of soil
 Disposing of wastes and controlling population of pests
Biodiversity and Species theories
 Evolution theory explain how life on the earth changes over
time though changes in the genes of populations (Wallace and
Darwin)
 Populations evolve when genes mutate and give some
individuals genetic traits that enhance their abilities to
survive and to produce offspring with these characters
(natural selection)
Process of Biological evolution by natural
selection
 Genes mutation
 Individual selection
 Population evolution
 Better adaptation
 Surviving and reproducing under existing environmental
conditions
‫مبانی و مفهوم انتخاب طبیعی‬
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‫گونه ها در مجادله دائمی با یکدیگر برای بدست آوردن غذا و سایر‬
‫منابع برای ادامه بقا هستند‪.‬‬
‫در داخل یک جمعیت گونه ای که دارای توانایی های نسبی است‬
‫شانس بیشتری برای بقا و تولید نسل دارد‬
‫این تواناییهای نسبی و مزیتها با ویژگیهای فردی ارگانیسم در داخل‬
‫جمعیت گونه خود مرتبت است‪.‬‬
‫این ویژگیهای بقا به ارگانیسم کمک میکند تا در طول فرآیند انتخاب‬
‫طبیعی بر جمعیت فایق آید‪.‬‬
‫فرایند انتخاب طبیعی هنگامی کامل مبگردد که این ویژگیها با تحول‬
‫ژنیتیکی در ارگانیسم همراه گردد‪.‬‬
‫تحول ژنتیکی از یک نسل به نسل بعدی را تکامل بیولوژیک‬
‫‪ Biological Evolution‬مینامند‬
Species Reaction to Environmental
Conditions Change
 Adapt to the new conditions through natural
selection
 Migrate to an area with more favorable conditions
 Become extinct
‫سه مفهوم غلط مصطلح در تئوری انتخاب طبیعی‬
‫‪ ‬مفهوم ‪ Survival of fittest‬بمعنی بقای نژاد قویتر یا ‪Survival of the‬‬
‫‪ strongest‬نیست بلکه بقای اصلح است‪ fitness .‬بمعنی توانایی تطابق با‬
‫تغییرات و شرائط محیطی بصورت مناسبتر برای تولید نسل بیشتر است‪.‬‬
‫‪ ‬ارگانیسم ویژگیهای خاص ‪ Traits‬را کسب کرده و توسعه میدهد زیرا‬
‫بدانها نیازمند است یا میخواهد به این ویژگیها دست یابد‪ .‬مثال گردن‬
‫زرافه است‪ .‬درحالیکه ارگانیسمی باقی میماند که شرایطش بهتر با محیط‬
‫تطبیق کند‪ .‬این ارگانیسم ژن ویژگی خاص را در اجدادش داشته که به او‬
‫برتری را نسبت به سایر ارگانیسم داخل جمعیت داده تا تولید نسل بیشتری‬
‫را صورت دهد‪.‬‬
‫‪ ‬تکامل از طریق انتخاب طبیعی براساس یک نقشه کالن و طراحی از‬
‫پیش تعیین شده و هدفدار طبیعت صورت گرفته و میگیرد تا گونه هایی با‬
‫توانایی تطبیق بیشتربا تغییرات محیطی به گونه های کاملتری مبدل‬
‫گردند‪ .‬از منظر علمی در روند تکامل هیچ هدف یا نقشه کالن علمی‬
‫کمال ژنتیکی مشاهده نمیشود‪ .‬بلکه تکامل یک فرایند اتفاقی‪ ،‬رندومی‬
‫وانشعابی ‪ branching‬میباشد‬
‫تاثیر روندهای طبیعی بر تکامل گونه ها‬
‫‪ ‬پروسه های جغرافیایی بر انتخاب طبیعی از طرق زیر تاتیر میگذارد‪:‬‬
‫‪ ‬از طریق جدایی صفحات قاره ای یا ‪ tectonic plates‬از ‪ 225‬میلیون‬
‫سال قبل که ‪ 5‬قاره بهم پیوسته بود ‪ Pangaea‬تا ‪ 135‬و ‪ 65‬میلیون سال‬
‫قبل که ‪ 4‬قاره و سپس اکنون که هر ‪ 5‬قاره جدا و شبه قاره هند از‬
‫پاتاگونیا جدا و به ارواسیا پیوست‪ .‬این شرایط دو تاثیر بر حیات در زمین‬
‫داشت‪ )1 :‬موقعیت و نحوه قرار گیری اقیانوسها و قاره ها بر اقلیم تاثیر‬
‫گذارد و برخی از گونه ها را نابود و گونه های دیگری ظاهر شدند‪)2 .‬‬
‫گونه با پیوستن به قاره جدید امکان تحول از طریق انتخاب طبیعی را‬
‫یافته و با جدا شدن از قاره قدیم امکان تطابق یا حذف را پیدا کردند‪.‬‬
‫برخی گونه ها نابود و برخی ظهور یافتند‪.‬‬
‫‪ ‬زمین لرزه با ایجاد شکاف در پوسته زمین زیستگاهها را از هم جدا و‬
‫زمینه تحول در گونه ها را بوجود آورد‬
‫‪ ‬آتشفشان ها با گسترش غبارها بعضی از زیستگاهها را نابود و بر گونه‬
‫ها تاثیر گذاردند‪.‬‬
‫تاثیر روندهای طبیعی بر تکامل گونه ها‬
‫‪ ‬تغییر شرایط حیات در زمین بدلیل پروسه تغییرات اب و هوایی‪:‬‬
‫گرم و سرد شدن مکرر کره زمین در طول حیات خود منجر به ازبین‬
‫رفتن برخی از گونه ها و ظهور گونه های مقاوم به شرایط جدید‬
‫محیطی‪ ،‬تغییر زیستگاهها‪ ،‬مهاجرت گونه ها به زیستگاههای جدید و‬
‫تکامل گونه در اثز تغییرات زیستگاهی منجر گردیده است‬
‫‪ ‬تغییر وضعیت زمین بدلیل برخورد اجرام آسمانی‪:‬‬
‫در طول زندگی چهار و نیم میلیارد ساله زمین تعدادقابل مالحظه ای از‬
‫اجرام آسمانی به کره زمین برخورد و شرایط اکوسیستمی آنرا تغییر و‬
‫زیستگاهها را جابجا کرده و بر حیات برخی از گونه ها تاثیر گذارده اند‪.‬‬
Affecting Biodiversity by:
 Speciation: under certain conditions, natural selection can lead to an entirely
new species and two species may arise from one. It takes place in two phases;
 Geographic isolation by: migration for food, earthquake, physical barriers
 Reproductive isolation
 Extinction happens when an entire species cease to exist.
 Endemic species are found in only one area and are especially vulnerable to
extinction.
 Background extinction: disappearance of species in low rate (1-5 for every one
million species).
 Mass extinction: is a significant rise in extinction rate (20-70% of species within
geological period of 5 million years) by catastrophic and widespread events.
Based on fossil evidence, Earth experienced 5 mass extinction during the last
500 million years (every 20-60million years). A big loss of 95% in 250 million
years ago.
 Human Activities
Conclusion:
As environmental conditions changes, the balance between formation of new
species and extinction of existing species determined the earth’s biodiversity.
Species Diversity and its importance
 Species Diversity: is an important characteristic of a
community and the ecosystem to which belongs. The number
of different species which an ecosystem contains (species
richness) combined with the relative abundance of
individuals within each of those species (species evenness).
‫ تنوع گونه ای عبارت است از تعداد مختلف گونه های موجو در یک اکوسیستم‬
‫(غنای گونه ای) همراه با فراوانی نسبی و تراکم هرگونه در بین گونه های دیگر‬
)‫(یکنواختی گونه ای‬
 Species richness normally is contrary to species evenness.
 SD of communities varies with their geographical location
and decline from equator toward the poles.
 The most species – rich ecosystems are tropical rain forests,
coral reefs, the ocean bottom zone, and large tropical lakes.
Species equilibrium model or theory of
island biogeography ‫نظریه تعادل گونه ها‬
 This mode introduce by Robert MacArthur and Edward o.
Wilson in 1960s and describe that; the number of different
species found in an island is determined by interactions of
two factors:
 The rate at which new species immigrate to the island and;
 The rate at which species become extinct, or cease to exist, on the island.
 In balance point or equilibrium point, the rate of species immigration and
extinction should balance so that neither rate increasing or decreasing sharply.
 Two features are effecting the migration and extinction of
species in this model:
 The size of island (the biggest has the more SD)
 The distance with mainland (the nearest is the richest)
This model is applicable to National Parks and protected areas
surrounded by development
Affects of species richness on ecosystems
‫ آیا انبوه گباهی موجب ارتقای غنای گونه ای در یک اکوسیتم میشود؟ و آیا غنای گونه ای موجب یایداری بیشتر‬
‫اکوسیستم میگردد؟‬
 The more diverse an ecosystem is, the more productive it will be,
because it produces more plant biomass which support a greater variety
of consumer species.
 The greater species richness and productivity as well as accompanying
web of feeding and biotic interaction in an ecosystem makes it more
stable or sustainable to stand with environmental disturbances such as
drought and insect infestations.
 David Tilman hypothesize: Communities with higher plant species
richness produce a certain amount of biomass more consistently than
communities with fewer species. Higher level of biomass less affect by
drought, more consume CO2 and N2.
 An average annual net primary productivity of an ecosystem reaches a
peak with 10-40 producer species. More than that does not necessarily
produce more biomass
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
Classification of species by using Niche
 Niche classified in terms of species roles within ecosystems
to five role.
 Certain species may play one or more of these roles:
 Native Species: are those that normally live and thrive in a particular
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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)
How do species interact
 Five basic types of interaction between species for sharing
limited resources such as food, light, shelter, and space:
 Interspecific competition: occurs when members of two or more species
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interact to gain access to the same limited resources
Predation: occurs when a member of one species (predator) feeds directly on
all or part of member of another species(prey)
Parasitism: occurs 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: is an interaction that benefits both species by providing each one
limited resources
Commensalism: is 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.