Species conservation strategies

Leucaena salvadorensis: genetic variation and conservationDavid Boshier

No Population, Country# trees in population

1 Nueva Esparta, El Salvador 16

2 San Antonio, Honduras 224

3 Rio Nacaome, Honduras 120

4 La Garita, Honduras 500

5 La Galera, Honduras 181

6 Calaire, Honduras 700

7 Charco Verde, Honduras 79

8 San Juan Limay, Nicaragua >1000

2

© CE Hughes

Nueva Esparta El Salvador

3

© DH Boshier

© DH Boshier

Calaire Honduras

4

© DH Boshier © DH Boshier

San AntonioHonduras

Rio NacaomeHonduras

5

© DH Boshier

© DH Boshier

6

© CE Hughes

L. leucocephala self compatible

7

© CE Hughes© CE Hughes

L. salvadorensisself incompatible

8

Conservation alternatives

• preservation of actual diversity

• conservation of evolutionary potential

• mantain options for future generations, while satisfying present needs

9

10

How big is “big enough”?

50/500 rule (Franklin 1980)

50 - inbreeding depression to acceptable level

500 - sufficient for new variation from mutation to replace that lost by genetic drift refers to effective population size (Ne) rather than survey numbers (N) – so may need many more! in trees Ne smaller than N due to: overlapping generations, dioecy, asynchronous flowering, fecundity differences between individuals

11

Where should we conserve?

In situ - reserve system of undisturbed, protected areas within natural distribution (ecosystem based)

Ex situ - artificial maintenance of populations outside natural distribution (species based)

In situ - Ex situ

12

Conservation of biodiversity in situ: trees as a paradigm

ideal reserve model

emphasis: large, continuous, protected areas

limitations: location, size, security, biology:– movement of animals– extensive distribution of many species– gene flow between populations– upland, non agricultural areas

essential but not sufficient13

Conservation of biodiversity ex situ: methods and limitations

seed banks - problems of regeneration

plantations - changes in gene frequencies, few populations

botanical gardens - deficiencies for gene pool conservation

14

© RBG Kew © RBG Kew

• useful, but resources limit application to few species (usually commercial)

• last gasp holding for highly endangered species

• complimentary to other approaches

Conservation of biodiversity ex situ: methods and limitations

15

a large number of individuals of many species have long ago ceased being ecologically (and evolutionarily) reproductive; they flower but set no seed, or if they set seed, the seedlings never lead to recruitment of adults. 16

© DH Boshier

© DH Boshier

These are the living deadJanzen 1986

Where should we conserve?

• In situ - reserve system of undisturbed, protected areas within natural distribution (ecosystem based)

• Ex situ - artificial maintenance of populations

outside natural distribution (species based)

• Circa situm - conservation within altered agricultural landscapes, within natural distribution

17

Conservation of biodiversity in practice: circa situm as a necessity?

• Majority of conservation in situ outside of reserves emphasises:

– trees outside of forests

– role of indigenous/local communities

– role of forest and land administrators

– compatibility between resource management systems and conservation objectives

18

Conservation of alleles

common - rare what proportion?

widespread - localised what scale?

widespread localised

common easy key

rare (<0.05) sample size luck

19

Widespread vs locally common alleles

frequency Pop 1 2 3 4

Allele a 0.500 0.320 0.450 0.550

b 0.250 0.030 0.050 0.050

c 0.230 0.400 0.450 0.350

d 0.020 0.250 0.050 0.050

20

Figure 2. Genetic similarities (Nei unbiased genetic distance) between L. salvadorensispopulations

21

Table 4. Gene flow (Nm - number of migrants per generation) below black diagonal and geographic distance (in km) above black diagonal between L. salvadorensis populations (details in Table 1). Correlation between gene flow and geographic distance: r = - 0.17

Figure 3. Relationship between gene flow between populations (Nm – number of migrants per generation) and geographic distance (km); based on data from Table 4

22

Leucaena salvadorensis

Conservation strategies – four groupsEl Salvador (country specific strategy)

Honduras (country specific strategy)

Nicaragua (country specific strategy)

FAO (international perspective)23

Leucaena salvadorensiseach group summarise on wall chart paper

Remember need a conservation objectiveprioritise actions – resources are limited

list the localised but common alleles?

list problems by type- genetic, which pops. too small? which are different?- other types of problems

which conservation methods - in situ, ex situ, circa situm?

who? will do, what? where?

how will you pay for it?

24