morphometrics: results & applications · 2018-09-28 · public service announcements • colony...

Morphometrics: Results & Applications

Public Service Announcements

• Colony Monitoring – Last Week

• 40 chicks: Started Growing the Primary Feathers

Time (Julian Day)

225 235 245 255 265

Ch

ick M

ass (

g)

0

100

200

300

400

500

0

100

200

300

400

500Mean +/- SD

Median

Min / Max

(August 17 - September 19, 2018)


• Colony Monitoring – Next WeekWho: Ciera, Jessie

When: Oct 10 (Weds)

Where: Leave OI at 3.15

• Colony Monitoring – This WeekWho: JJ, JoelleWhen: Oct 3 (Weds)

Where: Leave OI at 3.15

• Colony Monitoring – Next WeekWho: Nimz, Daisy

When: Oct 17 (Weds)

Where: Meet at FSP at 4.00


• Project

What: Project Statement (with 3 key papers) When: Via Email – by October 5 How: via email to [email protected]: Abstract (200 words): what / why ?

Include citations and attach pdfs

• Second Quiz

What: 5 points, 30 minutes

When: October 12 Topics:

morphometrics / necropsieslectures / readings / activities

mailto:[email protected]


• Quiz #2 – Readings:

• Quiz #2 – Lectures: 4, 5, 6

• Quiz #2 - Labs / Activities: Necropsies & Morphometrics

Necropsy Manual WTSH species account Articles

• Bull, L.S., et al. (2005). Patterns of size variation in the shearwater genus Puffinus. Marine Ornithology 33: 27–39.

• Serrano-Meneses, M.A., & Szekely, T. (2006). Sexual size dimorphism in seabirds: sexual selection, fecundity selection and differential niche-utilisation. Oikos 113: 385- 394.

Measure the following:

• Culmen length / depth• Head length• Wing length (chord)• Head length (head & bill)

Necropsies – External Observations

Morphometrics Data

ize

Documenting Age Classes

• Score for molt (primaries / tail)

• Record % of down

• Record brood patch

• Inspect sex organs• Measure the bursa

Morphometrics Data

NOTE: Expect normally distributed data

Unless different populations sampled

Sources of size variability – within a population:

- different condition / age (chicks vs adults)- sexual dimorphism (male size vs female size)

Sexual Size Dimorphism (SSD)• Definition: Species deemed sexually size dimorphic if

the average measurements of individual morphometricsdiffered between the sexes by > 5%. (Bull et al. 2005)

• Three Theoretical Explanations:

- Sexual Selection: If sexual selection more intense in one sex than other (via male-male competition or female choice) (Darwin 1871)

- Fecundity Selection: Larger females have higher reproductive success (higher fecundity: more eggs / larger eggs, male choice)

- Niche Separation: Males and females have different body sizes to avoid resource competition, or enhance feeding efficiency

Sexual Size Dimorphism (SSD)• Methods: Use phylogenetic comparative methods to test SSD. Compared families / subfamilies first, then species:

(Serrano-Meneses & Szekely, 2006)

Sexual Size Dimorphism (SSD)Rensch's rule: allometric law concerning relationship between extent of sexual size dimorphism (SSD) and which sex is larger.(Rensch 1950, Fairbairn, 1997).

Across species within a lineage, size dimorphism increases with increasing body size when the male is the larger sex, and decrease with increasing average body size when the female is the larger sex.

Examples of phylogenetic lineages that follow this rule include:

primates and pinnipeds


Sexual Size Dimorphism (SSD)Results: Compared species-specific SSD against:

- Display behavior (negative correlation)- Clutch size (positive correlation)- Egg size (positive correlation)


Sexual Size Dimorphism (SSD)Conclusions:

Seabirds do not follow Rensch’s rule.

Seabirds are socially monogamous whereas mammals and landbirds exhibit social polygamy; therefore sexual selection in seabirds is less intense than in these taxa.


Sexual Size Dimorphism (SSD)Conclusions:

Moderate effect of male display behaviour, although agility, as represented by selected scores, was a crude variable.

Males are larger, relative to females, in species where males display on the ground, whereas sexes are similar in species with aerial display.

Both clutch size and egg size correlate with SSD, however, relationships not consistent withfecundity selection hypothesis.


• Compare specimen size and shape (given their sex)

(Guicking et al. 2004)

• Sexual dimorphism: Males have larger tails and bills, wider tarsi.

• Males have wider bills (at base and minimum).

• Differences by locality in many traits, including tarsus length.

Morphometrics Application

Uses of Morphometrics

Bill Depth at Base (mm)

10 11 12 13 14 15

Bill

Dep

th (

mm

)

6.5

7.0

7.5

8.0

8.5

9.0

9.5

Pearson Correlation (r = 0.57, n = 12)

Sexually dimorphic traits are cross-correlated.

Uses of Morphometrics

Bill Depth at Base (mm)

10 11 12 13 14 15

Cu

lme

n L

en

gth

(m

m)

32

34

36

38

40

42

Pearson Correlation (r = -0.05, n = 12)

Sexually dimorphic / monomorphic traits are not cross-correlated with each other.

Uses of Morphometrics – 1A• To identify species / sub-species.

Uses of Morphometrics – 1B• To identify species / sub-species.

Methods:

Unstraightened wing chord from carpal joint to tip of longest primary. Caution taken to not flatten wings during measurements.

Culmen length from implantation of feathers to tip of curved bill, using digital caliper.

Bill depth measured at nostrils. Bill width measured at base of culmen.

Tarsus length taken with digital calipers, from the middle of the midtarsal joint to the distal end of the tarsometatarsus.

Personnel strictly followed protocol to assure consistency; Intra-observer variability in measurements expected (Barrett et al. 1987).

(Judge et al. 2014)

(Judge et al. 2014)

Results:

Wing chord measurements of adult petrels from Hawai’i significantly shorter than from Maui (P < 0.01).

Fledgling petrels from Kaua’i had significantly shorter wing chords than fledglings from Maui (P < 0.01).

Adult tarsus measurements from Hawai’i significantly shorter than from Maui (P < 0.01).

Tarsus measurements of Kaua’ifledglings smaller than those from Maui fledglings (P = 0.0002).

Uses of Morphometrics - 1

Discussion:

Long wings cost-efficient for long-distance flight; constraints in wing size due to energy required to replace feathers

Longer wings of Maui birds could facilitate travel to productive distant feeding areas

Genetic drift also could affect phenotypic traits; but research suggests selection on morphological differences in this species.

Little gene flow among Hawaiian Petrel populations: Kaua’i and Hawai’i petrels genetically distinct (FST = 0.05) (Wiley et al. 2012) .

Each colony may need to be considereda separate genetic management unit.

A single foraging trip for a Hawaiian Petrel over 10,000 km and two weeks. This individual tracked from Haleakala, Maui (USGS unpublished image, J. Adams)



• To confirm age class of specimens.

Those


Wing Chord (mm)

240 250 260 270 280 290 300

Co

un

t

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

• Determine the stage of development of the chick.

• Has the individual reached the “adult size” ?

272 mm


• Determine the stage of development of the chick.

• Control for “tag effects”

(Adams et al. 2009)

Tarsus Length (mm)

44 45 46 47 48 49 50 51 52

Ma

ss (

g)

150

200

250

300

350

400

450Linear Regression (r

2 = 0.46, n = 12)


• To assess “body condition”, correlate body mass (g) with a metric of size, usually the tarsus length (mm)

Larger birds are larger in every way…

But, given their size, some birds have more mass (positive anomaly) than others (negative anomaly)


• To assess body shape of specimens

Tarsus Length (mm)

44 45 46 47 48 49 50 51 52

Win

g C

hord

(m

m)

230

240

250

260

270

280

290

300

310

Pearson Correlation (r = 0.50, n = 12)Investigate changes in traits with respect to body size

Use traits not influenced by sexual dimorphism

• To assess the condition of individuals at once

Wing Chord (mm)

20 25 30 35 40 45 50

Bo

dy M

ass (

g)

50

100

150

200

250

300

Freeman Seabird Preserve

(n = 37, r = 0.82)


Wing Chord (mm)

20 25 30 35 40 45 50 55 60 65 70 75 80 85

Bo

dy M

ass (

g)

0

100

200

300

400

500

Aug. 21

Aug. 29

Sept. 5

Sept. 11

Freeman Seabird Preserve

• To assess the condition of individuals over time



• To quantify morphological differences in size and shape, related to differences in ecology

• Only species with wide distributions exhibit significant geographic variation in morphometrics

• No significant interaction between sex and population, suggests lack of geographic variation in magnitude of sexual dimorphism

(Bull et al. 2005)

Morphometrics Application➢ Objective:

• To describe the major patterns of size and shape variation of Puffinus species over their respective ranges.

• Addressed four questions:

- Do sympatric congeners differ in size and shape ?

- Do sexes of each Puffinus species differ morphometrically ?

- Do species exhibit interpopulation morphometric variation ?

- Does degree of sexual size dimorphism differ over species range ?

• Morphologic variation owing to sex and population was examinedfor each character by a mixed-model, two-way analysis of variance:

with sex as a fixed effect population as a random effect

(Bull et al. 2005)


➢ Methods:

Design provided tests of three null hypotheses:

i) no sexual dimorphism;

ii) no effect of population location;

iii) no geographic variation in sexual dimorphism (as indicated by sex × population interaction).

Test for effect of sex on the other morphometrics, with ANCOVA using body size (represented by TL) as a covariate

(Bull et al. 2005)


➢ Results: (Bull et al. 2005)

WTSH ♂ > ♀ (but less than 5% larger); Also found regional differences

WTSH measurements

• To identify the provenance (origin) of specimens (e.g., fisheries bycatch)


• Significant differences for most measurements between males / females

• Geographical differences between two colonies, reflect ecomorphologicaladaptations



➢ How to Take Standardized Measurements:

• Culmen length • Bill depth• Wing length (chord)• Head length

➢ The uses / interpretation of morphometrics data:

• Chick growth – colony monitoring• Bird Condition - necropsies

What You Need to Know

morphometrics: results & applications · 2018-09-28 · public service announcements • colony...

Documents