Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Salit Kark

Department of Evolution, Systematics and Ecology

The Silberman Institute of Life Sciences

The Hebrew University of Jerusalem

Conservation Biology (Ecology)

Lecture 3

Nov 2009

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Signed by over 150 governments in 1992 in Rio

Became effective as international law in 1993

First international agreement committing governments to comprehensive protection of the Earth's biological resources 

February 2004, 188 countries and the European Union had ratified the agreement; the U.S. was one of the last nations to sign.

THE CONVENTION ON BIOLOGICAL DIVERSITY (CBD)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

The CBD has three overall goals:

The conservation of biological diversity

The sustainable use of its components, and

The fair and equitable distribution of benefits derived from "genetic resources".

THE CONVENTION ON BIOLOGICAL DIVERSITY (CBD)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Participating governments agree to carry out various measures to conserve biodiversity:

to create national plans for protection of biodiversity.

to identify ecosystems, species and genomes important for conservation and sustainable use of biodiversity

to monitor biological diversity and any factors that might have impacts on it.

to establish a system of protected areas.

THE CONVENTION ON BIOLOGICAL DIVERSITY (CBD)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Participating governments agree to carry out various measures to conserve biodiversity:

to manage biological resources to ensure conservation and sustainable use

to rehabilitate and restore ecosystems

to take measures for ex situ conservation. 

The CBD includes agreements for using biological diversity. And governments must provide for "fair sharing" of the benefits derived from genetic resources.

THE CONVENTION ON BIOLOGICAL DIVERSITY (CBD)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

About 92% of plants worldwide are pollinated by animals.

There are more than 1200 vertebrate species and between 100,000 and 200,000 invertebrates involved in pollination of flowering plants.

30% of US food supply by volume depends on animal pollinators, of which bee species (Apoidea) are the most important.

but most crops in the USA and Australia are pollinated mainly by introduced honey bees.

Ecosystem services valueExample: Pollination servicesFrom: The Nature and Value of Australia’s Ecosystem Services: A Framework for Sustainable Environmental Solutions by Steven J. Cork and David Shelton (2000)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

The value of honey bees to agriculture in the USA is estimated to be US$2–8 billion annually.

Many farmers rely on pollinators of the European honeybee (Apis mellifera) that they import temporarily to crop fields to provide pollination during bloom.

Honeybees are not always the most effective pollinators of a given crop, and the number of honeybee colonies, both domesticated and feral, have declined by 50–70% since 1946.

Example: Pollination servicesFrom: The Nature and Value of Australia’s Ecosystem Services: A Framework for Sustainable Environmental Solutions by Steven J. Cork and David Shelton (2000)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services

Concern about this heavy reliance on one pollinator species.

A “pollination crisis” has been predicted in the US due to a major decline in honey bees caused by a range of diseases and mites.

Native, unmanaged bee populations also provide important pollination services to various crops, and are generally more diverse and are abundant near natural habitat

It is estimated that other pollinators could take up US$4–7 billion of the service in the USA if they and their habitat were present in sufficient amounts.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services

…observed declines in pollination rates and seed set in a range of crops and native plants

...possibly associated with less pollination by native bees due to urbanisation, land clearing and modern agriculture.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services

Claire Kremen’s study, Ecology Letters, 2004.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services

They studied 22 watermelon (Citrullus lanatus) fields located in California June to August 2000.

Farms varied in the proportion of natural habitat (riparian forest, chaparral and oak woodland) found nearby.

Also compared organic and 'conventional' farms

In northern California, 28 native solitary and two native social bee species pollinate watermelon

Assessed bee visitation to watermelon flowers by walking 50 m of row in 10 min.

Estimated the mean total number of pollen grains deposited by bees per flower.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services Kremen’s study:

For native bees, mean pollen deposition per flower was significantly related to proportion of riparian or upland habitat

no significant effect of farm-type (low power)

Model: if farmers were to rely entirely on native bee communities for pollination, their farms would need to be situated in areas containing ≥ 40% of natural habitat within a 2.4 km radius as natural habitat, or ≥ 30% within 1.2 km

Both the amount and the stability of pollination services from native bees increased with increased proportional area of upland habitats.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Example: Pollination services

In Australia, a range of native moths, beetles, flies, birds and marsupials are important pollinators of commercial crops.

However, the overall potential for native pollinators to substitute for honey bees is unknown.

Declining pollination rates of native vegetation in agricultural landscapes

Fragmentation and use of pesticides is having impacts on pollination services in Australia and other areas as well.

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Genetic Genetic

DemographicDemographic

Spatial: (m)population dynamicsSpatial: (m)population dynamics

Conservation biology

Population level considerations

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Relationship between population size and genetic variability

Population Genetics and Conservation

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

How do we estimate genetic diversity?

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

באוכלוסיה להיות יכול אחד שבלוקוס מהעובדה אחד נובעת מאלל יותר

2 : b ו- aאללים ab ,bb ,aa ים:גנוטיפ 3

אלל ap= 8/12= 0.67:תדירותאלל bq= 4/12= 0.33:תדירות

גנוטיפ aa:p2=0.672=0.44תדירותגנוטיפ bb:q2=0.332=0.11תדירות

בת –אוכלוסיהפרטים 6

הגרלהסטוכסטיו

ת

גנוטיפ ab:2pq=0.66•0.33=0.44תדירות

צפוי' פרטים 2.7 =6*0.44 מס

צפוי' פרטים 2.7 =6*0.44 מסצפוי' פרטים 0.7 =6*0.11 מס

3 תצפית:1תצפית: 2תצפית:

הנחזה סטיתמהצפוי

, קטנה אוכלוסיה" ולכן ניסוים " מספרקטן

מה תהיינה תוצאות (בהנחה ההגרלה לאחר דור

שכל פרט מחליף עצמו בפרט אחד)?

הוריאביליות הגנטית

Source Uriel Safriel

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

גנוטיפ :aaתדירותq2

גנוטיפ ab:2pqתדירות

p2

גנוטיפ :abתדירותגנוטיפ :bbתדירות

כאשר p היא aאלל תדירות

q היא bותדירות אלל

סלקציה בהעדרזו תדירות תישמר

לדור – מדור- ויינברג הרדי חוק

- מדור ישמר המשקל שווי אולםלדור

גדולות באוכלוסיות רקהגנוטיפים תדירות

עמידות את קובעתלגורמי האוכלוסיה

האקראית ההכחדה

דמוגרפית סטוכסטיותסביבתית סטוכסטיות

סטוכסטיות הקטסטרופות

את מקטינותהאוכלוסיה

- קורס ויינברג הרדי חוק

משתנה הגנטי ההרכב

האוכלוסיה עמידות

משתנהSource Uriel Safriel

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

כדי לא לאבד אללים נדירים שדווקא הם יסייעו להחלץ מהמצב

המסוכן של אוכלוסיה קטנההאוכלוסיה צריכה להיות גדולה

הקטנה דרסטית בגודל האוכלוסיה (קטסטרופה)

הקטנות ב –

שעור ההטרוזיגוטיות• מספר האללים בלוקוס •

מרובה-אללים מספר האללים הנדירים• שעור ההטרוזיגוטיות •

כתוצאה מירידה במספר האללים הנדירים

מספר האללים הנדירים •כתוצאה מירידה במספר

האללים בלוקוס מרובה-אללים

עליה בהסתברות ההכחדה

צוואר הבקבוק

מצב מסוכן עוד יותראם

צוואר הבקבוק

ארמתך

Nגבוה

מסוכן לכשעצמו

שונות גנטית נמוכה

↓פגיעות להכחדה

כדי לא לאבד אללים מלוקוס מרובה-אללים אוכלוסיה צריכה להיות גדולה

N נמוך

שונות גנטית גבוהה

עמידות להכחדה

Source Uriel Safriel

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

What is a Population Bottleneck? An observable and dramatic collapse

in numbers

0

200

400

600

800

1000

1200

1400 N

TIME

RECOVERY

CRASH

Bottleneck

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

0

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

N

TIME

CRASHINSULAR ORCAPTIVEBottleneck

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Whatever the circumstances: a bottleneck is equivalent to taking a relatively small sample of items, in

this case genes, from a large population(game…)

Salit Kark, Conservation Biology, Hebrew University, Lecture 2

Loss of genetic variability has multiple aspects

• specific alleles will either be lost or retained (maintained)

• genetic variance (or heterozygosity) will be lost