When conifers meet Greg Jordan Tim Brodribb Pinaceae - - PowerPoint PPT Presentation

Greg Jordan Tim Brodribb

When conifers meet

Pinaceae Podocarpaceae

North versus South

Pinaceae

Equator

Podocarpaceae

Equator

Species richness in equal area grid cells

(2° latitude)

Dispersal limitation?

• evidence for "rapid" dispersal of some

Podocarpaceae [at least] – long history at high southern latitudes [≥ 150 million years] – appeared in SE Asia ≤ 20 million years

• r niche constraints?
• Physiology

– podocarps hate frost, dry climates & fire – pines hate closed forest

• is this true now?
• was it true in the past?

Pinaceae and Podocarpaceae occupy different climate spaces now

20 40 60 80 100 120

• 38 -34 -30 -26 -22 -18 -14 -10 -6 -2

2 6 10 14 18 22

Number of species Mean minimum temperature of the cold month (°C)

20 40 60 80 100 120 140

Number of species Precipitation of the driest quarter (log scale)

Podocarpaceae are absent from very frosty climates Podocarpaceae occupy wetter climates than Pinaceae

Two regions of overlap

Pinaceae Podocarpaceae

Equator Equator

Similar contrasts in the regions of overlap

10 20 30 40 50 60

Number of species Precipitation of the driest quarter (log scale)

5 10 15 20 25 30 35 40

• 38 -34 -30 -26 -22 -18 -14 -10 -6 -2

2 6 10 14 18 22

Number of species Mean minimum temperature of the cold month (°C)

The contrasting climates are not just because of the different climates in the SH & NH

Was this true in the past?

• Ancestral state reconstructions?
• Other ways?

extinction and directional selection in conifers poses problems for ancestral state reconstruction

• conifer phylogenies clades with very long stems
• extensive fossil evidence of climate driven extinction

1,2

Crisp MD, Cook LG. 2011. Cenozoic extinctions account for the low diversity of extant gymnosperms compared with angiosperms. New Phytologist 192: 997-1009. Nagalingum NS, Marshall CR, Quental TB, Rai HS, Little DP, Mathews S. 2011. Recent synchronous radiation of a living fossil. Science 334: 796-799. 1 2

Phylogenetic endemism

• weights diversity according to past selection

– upweights rare old clades – i.e. ones that have been selected against...

species richness for all conifers Phylogenetic endemism for all conifers

As a sign of past processes

• rare old clades are presumably rare because of

past selection

• these clades tend to retain ancient,

unfavoured physiology

• high phylogenetic endemism relative to

species richness can indicate ancestral states

Phylogenetic endemism in climate space

• 10

10 30 50 70 90 110 130

• 38 -34 -30 -26 -22 -18 -14 -10
• 6
• 2

2 6 10 14 18 22

Phylogenetic endemism Mean cold month minimum temperature (°C)

(Pinaceae vs Podocarpaceae)

20 40 60 80 100 120

Number of species

Both clades show a mode in phylogenetic endemism at a cold month minimum temperature of ~0°C Divergent radiations: Pinaceae into frosty places Podocarpaceae into tropical rainforest

Summer temperature (proximity to tree line)

Podocarpaceae moved into warmer climates? Pinaceae moved into colder climates

20 40 60 80 100 120 140 160 180

Nu ber of species

20 40 60 80 100 120 140

6 8 10 12 14 16 18 20 22 24 26 28 30 32 Phylogenetic endemism mean temperature of the warmest month

Dry climates

Podocarpaceae have not changed – always wet Pinaceae were always drier than Podocarpaceae, but have radiated further into dry climates

20 40 60 80 100 120 140

Number of species

20 40 60 80 100 120

4 16 36 64 100 144 196 256 324 400 Phylogenetic endemism dry month precipitation (mm)

Mean annual precipitation

Both clades have moved to drier climates, but especially Pinaceae

20 40 60 80 100 120 140 160 75 100 200 500 1000 2000 5000 Phylogenetic endemism mean annual precipitation (mm) 20 40 60 80 100 120 140 160 Number of species

Overall

• Podocarpaceae and Pinaceae are strongly

ecologically differentiated

• This appears to have always been the case

– niche conservatism – especially for Podocarpaceae

• Pinaceae constrained by the Equator
• Phylogenetic endemism tells us about the

past, not just the present