Species Traits as Filters of Climate-Induced Range Expansion

D I A N E D E B I N S K I J E R E M Y K E R R A N D M A X I M L A R R I V É EI OWA STAT E UN I V E R S I T Y , UN I V E R S I T Y OF OTTAWA , I N SE CTA R I UM D E MON T R É A L

I N T R O D U C T I O N

• As climate warms, species are expected to move poleward or up in elevation to track the environmental conditions to which they are most adapted (Parmesan et al. 1999; Chen, Hill et al. 2011)

• However, this movement and the subsequent colonization of new habitat may be affected by species-specific habitat affinities and life history traits that facilitate or impede range expansion

map from vidiani.com

0°C

Warming over time

Diagram courtesy of Jay Fitzsimmons

I N T R O D U C T I O N

• Even if the “thermal envelope” is ideal, the vegetation conditions or other environmental parameters may not be conducive

• Similarly, traits such as wingspan or voltinism may act as a filter in defining which species can successfully colonize new regions

• Build on use of trait analysis:

• Ockinger et al. (2010) Eco. Letters Debinski et al. (2013) Ecology

http://www.greenpeace.org/canada/en/campaigns/forests/boreal

I N T R O D U C T I O N ( C O N T. )

• Using massive, long-term butterfly datasets, we asked:

1. How do abundance patterns change over time from early vs. recent time?

• 2. How do butterfly traits affect the changes in abundance?

Red to Blue = High to low

butterfly species richness

• 1901-1970

• 1985-2010

Red to Blue = Increasing to decreasing butterfly species richness in the

past century

H Y P O T H E S E S

Species with larger wingspans and more generations per year would respond more quickly to climate change and thus show positive trends in abundance.  

Generalist species would show increasing trends, whereas specialists would be more likely to show decreasing trends.

Compared species abundance patterns from historical time periods (1901-1970) and recent time periods (1985-2010).

Restricted analysis to ~100 species that were well sampled (i.e., they had abundances of 50 or more during each time period)

B U TT E R F LY M E T H O D S : B U TT E R F LY DATA

Wingspan

Preferred habitat - open (e.g., grassland), closed (e.g., forest) or edge (e.g., riparian edge).

Moisture - wet habitat, dry habitat or both.

Voltinism - 1-3 generations per year.

B U TT E R F LY M E T H O D S : T RA I T S

Sources: Scott, Opler, BAMONA, Iftner, Acorn, Layberry, xerces.org., natureserve.org

Grid cells at a 400 km resolution

(equal area projection)

B U TT E R F LY M E T H O D S

A standardized abundance was calculated for each species by subtracting the mean count over all species and locations within each time frame.

For each species at each location standardized abundance at time t1 was subtracted from the standardized abundance at time t2 to calculate a standardized difference in abundance.

We then used a linear model to model standardized difference in abundance:

std_diff ~ y + wingspan + habitat_type + moisture + voltinism + wingspan * y + habitat_type * y + moisture * y + voltinism * y

Where y= latitude

B U T T E R F LY M E T H O D S : S TA N D A R D I Z I N G A B U N D A N C E

R E S U LT S : T RA I T S A N D A B U N DA N C E C H A N G E S

•

Table 2: Coefficients from the full model with all main effects for difference in standardized abundance.  All factors were significant.

  Model

wingspan 1.47

Moisture: dry (base= wet) -51.66

moisture: both (base=wet) 38.15

Voltinism2 (base=1) 73.58

Voltinism3 (base=1)

131.58

Note: interaction with lati-tude was also significant for

all factors

P I E R I S R A P A E , P H Y C I O D E S P U C H E L L A , P A P I L I O Z E L I C A O N , A N D C U P I D O A M Y N T U L A .

HABITAT GENERALISTS

http://butterfliesofamerica.com/phyciodes_pulchella_camillus_live1.htm

http://www.butterfliesandmoths.org/species/Cupido-amyntula

3 G E N E RAT I O N S P E R Y E A R

• Pieris rapae, Vanessa cardui, and Vanessa virginiensis.

http://commons.wikimedia.org/wiki/File:Pieris_rapae_total_Richard_Bartz.jpg

http://commons.wikimedia.org/wiki/File:Vanessa_cardui_3_Luc_Viatour.jpg

http://www.learnaboutbutterflies.com/North%20America%20-%20Vanessa%20virginiensis.htm

R E S U LT S : PROPORTIONAL CHANGE IN ABUNDANCE between 1901-1970(t1) and 1985-2010 (t2) for species with 1 (left), 2 (middle), or 3 (right) generations per year.

• 1 Generation • 2 Generations • 3 Generations

S U M M A RY: A B U N DA N C E PATT E R N S

Species with the following traits showed increases in relative abundance over time:

o Larger wingspans

o More generalized habitat requirements

o Higher growth rates (voltinism)

No significant differences relative to habitat affinities

S Y N T H E S I S

• Our results support the hypothesis that traits are indeed acting as an important filter differentiating which species will respond most quickly to climate change.

AC K N O W L E D G E M E N T S

University of Ottawa, Distinguished Visiting Researcher Program

Iowa State University, Faculty Professional Development Assignment

E-butterfly: www.e-butterfly.ca

Statistical consulting: Lendie Follett, ISU