Dark diversity dynamics linked to global change: taxonomic and functional perspective

Diego P.F. Trindade

University of Tartu - Macroecology workgroup

Supervisors:
Prof. Meelis Pärtel
Assoc. Prof. Carlos P. Carmona

Community assembly

Community assembly

Filtered species pool

Dark diversity

Dark diversity

Set of species or traits present in the region, locally suitable, but absent

Dark diversity cannot be seen

But we can estimate it

But we can estimate it

Co-occurrence methods

Functional dark diversity

Functional dark diversity

Portion of the functional space that could be locally ocupied but is absent

Why is dark diversity important?

Why is dark diversity important?

• How the filtering process operates from regional to local scales;

• How realized each local community is: community completeness;

• When functional traits are included: why species are absent;

• Nature conservation

Global change and biodiversity reshuffling

Global change and community assembly

Global change and community assembly

Climate and land-use change affect biodiversity across scales

Biodiversity change is time-delayed

Dark diversity and global change

Dark diversity as a tool to assess and quantify biodiversity change across space and time?

Thesis structure

• 1^st paper
• 2^nd paper
• 3^rd paper

• Theoretical framework / review

• How observed and dark diversity may change

• Temporal lags involved

• Sedimentary pollen data (20 lakes)

• Dark diversity dynamics over 14500 years

• Taxonomic and functional facets

• Functional traits (seed weight, height, specific leaf area, clonality)

• Lichen dataset along an elevational gradient;

• How climate change may affect the species pool

• Dark diversity, functional traits and nature conservation

Main hypotheses

• Taxonomic and functional observed and dark diversity are expected to increase towards more benign conditions;

Larger species pools

Main hypotheses

• Taxonomic and functional observed and dark diversity are expected to increase towards more benign conditions;

• Over time, dark diversity depicts species in expansion lag;

Suitable but absent over time

Main hypotheses

• Taxonomic and functional observed and dark diversity are expected to increase towards more benign conditions;

• Over time, dark diversity depicts species in expansion lag;

• Traits related to low dispersal ability and stress tolerance are expected to be found more often in dark diversity;

Low dispersal ability and stress tolerance

Main hypotheses

• Taxonomic and functional observed and dark diversity are expected to increase towards more benign conditions;

• Over time, dark diversity depicts species in expansion lag;

• Traits related to low dispersal ability and stress tolerance are expected to be found more often in dark diversity;

• Dark diversity reveals species and traits threatened to go extinct or that could be focused on restoration activities

Main findings

1^st paper:

Temporal lags in observed and dark diversity

1^st paper:

Temporal lags in observed and dark diversity

Dark diversity enables decomposing biodiversity change and detect temporal lags;

Dark diversity creates windows of opportunities to protect and restore biodiversity.

1^st paper:

Temporal lags in observed and dark diversity

Dark diversity enables decomposing biodiversity change and detect temporal lags;

Dark diversity creates windows of opportunities to protect and restore biodiversity.

2^nd paper: Vegetation dynamics over 14500 years

2^nd paper: Local and species pool gains over time

Less harsh conditions after the Late Glacial period and the Late Holocene boosted biodiversity

2^nd paper: Local and species pool gains over time

Less harsh conditions after the Late Glacial period and the Late Holocene boosted biodiversity

Dark diversity increased faster than observed diversity

Indication of expansion lag

Dark diversity reveals taxa in expansion lag

Dark diversity increased faster than observed diversity

Indication of expansion lag

Dark diversity reveals taxa in expansion lag

Highly suitable taxa that persisted in dark diversity

Fast life-history traits linked to expansion lags

These taxa were mostly: shorter, small seeded and broad-leaved

Indication of dispersal limitation and stress intolerance

No functional expansion lags

Functional space available mostly occupied - high functional completeness

Niches created after the LG and Late Holocene were rapidly occupied

No functional expansion lags

High functional redundancy at the species pool level

Indication of high stability/resilience

3^rd paper:

Dark diversity and functional traits enhance nature conservation of lichens

3^rd paper:

Functional traits

• Growth form: Crustose, Foliose, Fruticose;

• Photobiont type: Green algae, Trentepohlia;

• Reproduction: Sexual, Asexual

Conservation or restoration?

Less harsh conditions = larger pools

Larger pool of lichens towards less harsh environments

Less harsh conditions = larger pools

Larger pool of lichens towards less harsh environments

Larger and more complete pools

Larger and more complete pool of lichens towards less harsh environments

Warm sensitive and strict biotic interactions

Macrolichens (Foliose/Fruticose) and lichens reproducing sexually are more threatened

Biotic interactions not dispersal limitation seems to be more important

Crustose lichens with green algae photobiont may be more successful in restoration activities

Conservation or restoration?

Conservation and Restoration at warmer sites

Conservation at cooler sites

Conclusions

• Observed and dark diversity of both plants and lichens generally increased towards less harsh conditions;

• Dark diversity reveals how much, how fast and in what direction species pools are changing;

• Functional traits revealed why species were in the dark diversity of both plants and lichens, and in expansion lag;

• Dark diversity and functional traits can be used to guide nature conservation plans, focusing on the whole species pool.

Thank you!

Thank you!

Thank you!

Additional slides

Dark diversity estimation

Dark diversity reveals taxa in expansion lag

PCA traits - pollen

PCA traits - pollen

Adding highly suitable taxa to observed

Removing closer sites