Cenozoic dynamics of beta diversity of angiosperm woody plants in the East Asian islands

1. Cenozoic dynamics of beta diversity of
angiosperm woody plants in the East Asian islands
Ikari, Shogo1
Takayuki, Shiono2
Yasuhiro, Kubota2
1 Graduate School of Engineering Science, Osaka University, Osaka, Japan
2 Faculty of Science, University of the Ryukyus, Okinawa, Japan

2. How climate change affects community assembly processes?
Pereira et al. (2010), ‘Scenarios for Global Biodiversity in the 21st Century’,
Science 330 (6010), p. 1496-1501.
Global warming causes poleward/upward range shift
(e.g., Sorte & Tompson, 2007; Kelly & Goulden, 2008)

3. How climate change affects community assembly processes?
Pereira et al. (2010), ‘Scenarios for Global Biodiversity in the 21st Century’,
Science 330 (6010), p. 1496-1501.
Paleoclimatic impacts on biodiversity
provides opportunities to examine how
warmer climate affects species assembly.
Global warming causes poleward/upward range shift
(e.g., Sorte & Tompson, 2007; Kelly & Goulden, 2008)

4. β diversity informs about assembly processes
species
site
1
site
2
site
3
site
4
a1
a2
a3
a4
a5
a6
a7
a8
a9
Beta partitioning approach by Baselga (2010)
• Local extinction/speciation
• Dispersal lag
Turnover: species replacement Nestedness: species loss/gain
Example
• Environmental filtering
• Dispersal limitation
species
site
1
site
2
site
3
site
4
b1
b2
b3
b4
b5
b6
b7
b8
b9
Site 1
Site 2
Site 3
Site 4
Source land
Site 1
Site 2
Site 3
Site 4
mountains
Temperature
gradient
Example
Corresponding processes Corresponding processes

5. β diversity informs about assembly processes
Beta partitioning approach by Baselga (2010)
Turnover component (βsim)
• Unsensitiveness to data bias
• Frequently used in fossil research
e.g., Darroch et al., 2014; He et al., 2018
species
site
1
site
2
site
3
site
4
a1
a2
a3
a4
a5
a6
a7
a8
a9
Turnover: species replacement
Example
• Environmental filtering
• Dispersal limitation
Site 1
Site 2
Site 3
Site 4
mountains
Temperature
gradient
Corresponding processes

6. Drivers of distance dependent turnover
Environmental filtering Dispersal limitation
(Species sorting)

7. Hypothesis
• Distance-dependency of species turnover is mitigated in the past warm
and stable ages, Tertiary periods, because of weakened climate-driven
environmental filtering.
• Distance-dependency becomes stronger in colder ages, after Quaternary
ice ages, under intensified environmental filtering
• Climate stability also moderates distance-dependency by softening
dispersal limitations.

8. Material: woody plants in the East Asian archipelago
High species richness
(Kubota et al., 2015)
Frigid to subtropical climate
20℃ represents subtropical/temperate
threshold
Climatic sensitive nature
(Niche conservatism)
Habitat/food for many other taxa
(Willis & MacDonald, 2011)
→ Ripple effects on ecosystem
Shiono et al., 2018
Analogous to current tropicalization
of temperate regions
Historical imprints of
land-bridge connection
and insularity
Suitable taxon to examine
effects of climate change

9. Method
Study site classification using hierarchical clustering
Statistical modelling
Negative exponential model following Kusumoto et al.
(2021) using spatial/climatic distance as explanatory
variables
Spatial distance
Geodesic distances between centre of sites
Miocene (Frigola et al., 2018), Pliocene, Pleistocene and LGP
(http://paleoclim.org/), and the Present (JMA, 2002).
*For Oligocene, Miocene temperature is used due to lack of data
Beta diversity
Genus-level pairwise βsim (turnover component) is
calculated for sites with more than 10 genera
Climatic distance
Difference in temperature in each geological ages
between sites
Data sets
Fossil occurrences through Cenozoic
7,468 data points; 310 genera & 95 families

10. Result
Spatial turnover coefficients
(negative exponential model)
Climatic turnover coefficients
(negative exponential model)
climatic distance is represented by
difference in mean annual
temperature between subregions
Oligocene Miocene Pliocene Pleistocene LastGlacial Holocene Present
Error bars represents 95 CI
Spatial/climatic distance dependent turnover became clear only after last glacial period

11. Oligocene Miocene Pliocene Pleistocene LastGlacial Holocene Present
Oligocene Miocene Pliocene Pleistocene LastGlacial Holocene Present
Spatial turnover
Climatic turnover
Result
Spatial/climatic distance dependent turnover became clear only after last glacial period

12. Weakened/intensified climate-driven environmental filtering
In warmer ages, when most of the
archipelago was subtropic,
temperature gradient would not
drive compositional differences
On the other hand, in colder ages,
climatic gradients regulated genus
composition

13. Dispersal release
When the climate was warm and stable, there would be
enough time to reach all the places that the climate niche
would allow.
→analogous to taxa with higher dispersal abilities
• spatial turnover structure can be very weak in aquatic
microorganisms (Bell, 2010)
• a lower proportion of turnover explained by spatial distance in
taxa with high dispersibility in a freshwater community
(Astorga et al., 2012)

14. Notes and implications
Method might also matter
Time-averaging through longer period enables us to see long-term
patterns while with risks of regarding species that were not present at
the same time are considered to have coexisted at the same site
Is the future really analogous to the past?
Warm and stable climate resulted in homogeneous biodiversity
distribution. However, what happens under the current rapid and
unstable warming is unknown. Studies with finer time scales would
provide further insights.

15. Summary
What we wanted to know:
• Distance-dependency of beta diversity in the fossil assemblages and its
patterning in different geological ages under warmer or cooler conditions.
• The impact of paleoclimate changes on large-scale species sorting and
dispersal processes in the past.
What we found:
• Spatial/climatic distance dependent turnover appears only after last
glacial period, suggesting that warmer ages imposed weakened species
sorting and dispersal limitations.
Significance:
• Showing that climatic conditions have affected the presence/absence of
distance-turnover relationships, while suggesting cautions when using
past climate effects on biodiversity to predict the future change.