Tag Archives: Anolis ferreus

Subfossil Record Reveals Human Impacts on a Lesser Antillean Endemic Anole

Figure 2: Landmarks (black point circled in white) and sliding landmarks (black points) used in the geometric morphometric analysis.

Figure 1. Landmarks (black point circled in white) and sliding landmarks (black points) used in the geometric morphometric analysis.

The knowledge of the past squamate fauna of the Guadeloupe islands (French Lesser Antilles) dramatically increased these last years in the framework of two European paleontological research programs. New archaeological and paleontological excavations (about which I previously talked) have been conducted and led to the discovery of thousands of squamate remains allowing to complete the pioneering works conducted by G. K. Pregill in the 90’s (Pregill et al., 1994). Results obtained on iguanas (Bochaton et al., 2016b), galliwasps (Bochaton et al., 2016a), ameivas (Bochaton et al., 2017a) and other taxa (Bailon et al., 2015; Bochaton et al., 2015; Boudadi-Maligne et al., 2016) point to high extirpation and extinction rates, mainly taking place during the last centuries after the European colonization of the archipelago and probably in relation to introduction of exogenous competitors and predators, as well as the practice of intensive agriculture.

In the middle of all of these extinctions, anoles, which are still very common in Guadeloupe, appeared to be kind of indestructible and were apparently not impacted at all by recent anthropogenic disturbances. However, the study of a huge assemblage of anole remains from Marie-Galante Island dated from Late Pleistocene to the 14th century reveals that this first impression was far from true.

Nearly 30,000 anole remains coming from several deposits were investigated using a combination of morphological and morphometric approaches. Size estimations (see Bochaton, 2016; Bochaton and Kemp, 2017) indicate that whatever the stratigraphic layer they come from, fully mature individuals range in three groups of Snout-Vent Length (SVL) size (Figure 2).

Figure 2.  SVL reconstructed on the basis of fully mature humeri (N = 66) with the results of a mixture analysis indicating a trimodal distribution. MTMS1, minimal theoretical maximal size obtained from the smallest fully mature humerus; MTMS 2, minimal theoretical maximal size obtained from the largest immature humerus; MTMS 3, minimal theoretical maximal size obtained from the smallest mature humerus included in the intermediately sized group.

Figure 2. SVL reconstructed on the basis of fully mature humeri (N = 66) with the results of a mixture analysis indicating a trimodal distribution. MTMS1, minimal theoretical maximal size obtained from the smallest fully mature humerus; MTMS 2, minimal theoretical maximal size obtained from the largest immature humerus; MTMS 3, minimal theoretical maximal size obtained from the smallest mature humerus included in the intermediately sized group.

These SVLs partly match those of the females (max 75mm SVL) and males (max 120 mm SVL) of the modern solitary Marie-Galante anole (Anolis ferreus). However, a third group of fossil specimens of very large size reaching 150mm SVL also occurred in the deposits and has no modern counterpart on the island. Still, morphological analysis indicates that these large specimens were also A. ferreus. A geometric morphometric analysis (Figure 1, above) was also conducted on dentaries of Marie-Galant fossils and included in a modern sample of Lesser Antillean anoles.
Figure 3. Two first axes of the PCA conducted on shape data collected for fossil and modern A. ferreus dentaries showing a diminution of morphological variability between fossil and modern anoles.

Figure 3. Two first axes of the PCA conducted on shape data collected for fossil and modern A. ferreus dentaries showing a diminution of morphological variability between fossil and modern anoles.

This analysis reveals a strong heterogeneity of the morphology of the dentary mostly depending of their size (allometry). The three fossil size groups are however closer to modern A. ferreus than to any other modern taxa and are linked by a common allometric relationship between their size and shape which differs from modern A. ferreus. The morphological variability of the fossil dentaries is also higher than that of modern A. ferreus (Figure 3).

These results indicate that all fossils are likely to correspond to A. ferreus. However, fossil representatives are more morphologically variable in terms of size, shape, and allometry than modern A. ferreus.The morphology of fossil A. ferreus remained stable during more than 30,000 years before an abrupt change that occurred during the last centuries. There is, however, a void of fossil data during the modern period which precludes linking this reduction of morphological variability between fossil and modern A. ferreus to a distinct event. Yet, this phenomenon is contemporaneous to the numerous extinction events documented on Marie-Galante and is thus very likely to be also related to the anthropization of the island.

This study also provides a strong argument again the hypothesis of the past occurrence of a second anole species smaller than modern A. ferreus on Marie-Galante and used to explain the large size reached nowadays by this insular solitary anole.

More details can be found in the publication of this work:

Bochaton, C., S. Bailon, A. Herrel, S. Grouard, I. Ineich, A. Tresset, and R. Cornette. 2017b. Human impacts reduce morphological diversity in an insular species of lizard. Proc. R. Soc. B 284:20170921.

References

Bailon, S., C. Bochaton, and A. Lenoble. 2015. New data on Pleistocene and Holocene herpetofauna of Marie-Galante (Blanchard Cave, Guadeloupe Islands, French West Indies): Insular faunal turnover and human impact. Quaternary Science Reviews 128:127–137.

Bochaton, C. 2016. Describing archaeological Iguana Laurenti, 1768 (Squamata: Iguanidae) populations: size and skeletal maturity. International Journal of Osteoarchaeology 26:716–724.

Bochaton, C., and M. E. Kemp. 2017. Reconstructing the body sizes of Quaternary lizards using Pholidoscelis Fitzinger, 1843 and Anolis Daudin, 1802 as case studies. Journal of Vertebrate Paleontology 37:e1239626.

Bochaton, C., R. Boistel, F. Cassagrande, S. Grouard, and S. Bailon. 2016a. A fossil Diploglossus (Squamata, Anguidae) lizard from Basse-Terre and Grande-Terre islands (Guadeloupe, French West-Indies). Scientific Report 28475:1–12.

Bochaton, C., S. Grouard, R. Cornette, I. Ineich, A. Tresset, and S. Bailon. 2015. Fossil and subfossil herpetofauna from Cadet 2 Cave (Marie-Galante, Guadeloupe Islands, F. W. I.): Evolution of an insular herpetofauna since the Late Pleistocene. Comptes Rendus Palévol 14:101–110.

Bochaton, C., S. Bailon, I. Ineich, M. Breuil, A. Tresset, and S. Grouard. 2016b. From a thriving past to an uncertain future: Zooarchaeological evidence of two millennia of human impact on a large emblematic lizard (Iguana delicatissima) on the Guadeloupe Islands (French West Indies). Quaternary Science Reviews 150:172–183.

Bochaton, C., R. Boistel, S. Grouard, I. Ineich, A. Tresset, and S. Bailon. 2017a. Evolution, diversity and interactions with past human populations of recently extinct Pholidoscelis lizards (Squamata: Teiidae) from the Guadeloupe Islands (French West-Indies). Historical Biology.

Boudadi-Maligne, M., S. Bailon, C. Bochaton, F. Cassagrande, S. Grouard, N. Serrand, and A. Lenoble. 2016. Evidence for historical human-induced extinctions of vertebrate species on La Désirade (French West Indies). Quaternary Research 85:54–65.

Pregill, G. K., D. W. Steadman, and D. R. Watters. 1994. Late Quaternary vertebrate faunas of the Lesser Antilles: historical components of Caribbean biogeography. Bulletin of Carnegie Museum of Natural History 30:1–51.

Fill In The Blank: Obscure Anole Life History Traits

In collaboration with the Conservation Biology course taught by Dr. Karen Beard here at Utah State University, where I am a Ph.D. student, I have been involved in gathering life history data on ~400 species of reptiles that have been introduced outside of their native ranges for an analysis of how life history traits (e.g., diet, fecundity, longevity) interact with other factors to influence the likelihood of successful establishment. Appendix A of Fred Kraus’ 2009 book Alien Reptiles and Amphibians is the source of the species list we are using, and included in this analysis are 26 species of Anolis. This is where you come in.

First, we coded all anoles as (i) sexually-dichromatic, (ii) diurnal, (iii) non-venomous, (iv) oviparous, (v) omnivores that lack (vi) temperature-dependent sex determination and (vii) parthenogenesis. Is anyone aware of any exceptions to these seven generalizations?

Second, we searched for data on clutch size, clutch frequency, incubation time, and longevity. The Anole Classics section of this site and the Biodiversity Heritage Library were particularly useful. After conducting what I feel to be a pretty thorough literature scavenger hunt, I am forced to conclude that some of these data simply do not exist at the species level for all of the species we’re interested in, or are not explicitly stated in a way that is obvious to a non-anole-expert. Of course, there is a lot of literature, including many books that I don’t have access to, and there are also lots of credible observations that don’t get published. I’m hoping that some of the readership here can help fill in at least some of the blanks in the table below. As one member of the team, I did not collect all of the data that are filled in myself, nor have I personally vetted every value, so if you spot an error please do point it out.

Two important points:

  1. Many environmental factors obviously influence the life history parameters of our beloved and wonderfully plastic reptiles, so we appreciate that many of these values would be better represented by ranges and are dependent on latitude, altitude, climate, and many other factors. Where a range is published, we are using its median value.
  2. I should also emphasize that, because of the large size of this study and the diversity of taxa included (ranging in size from giants like Burmese Pythons, Nile Crocodiles, and Aldabra Tortoises to, well, anoles and blindsnakes), it is more important for the data to reflect the relative values of these life history parameters across all anoles (and all reptiles) than it is to specifically and precisely represent all known variation within a given species of anole.

Without further ado (for your enjoyment, and because I know from my own blog that nobody reads posts lacking pictures, I’ve embedded an image of each species):

Species Median clutch size Median clutches per year Incubation time (days) Maximum longevity (months)
A aeneus
A. aeneus
2
A baleatus
A. baleatus
A bimaculatus
A.bimaculatus            
2 43 84
A carolinensis
A. carolinensis
1.15 6  41.5 65
A chlorocyanus
A.chlorocyanus
1 18
A conspersus
A. conspersus
1
A cristatellus
A. cristatellus
2.5 18 83
A cybotes
A. cybotes
1 18 45
A distichus
A. distichus
1 16 45.5
A equestris
A. equestris
1 1 48 149
A extremus
A. extremus
A ferreus
A. ferreus
1 18
A garmani
A. garmani
1.5 18 67
A grahami
A. grahami
1
A leachii
A. leachii
A lineatus
A. lineatus
A lucius
A. lucius
1 3.5 60
A marmoratus
A. marmoratus
2  50
A maynardi
A. maynardi
A porcatus
A. porcatus
1 18 63.5
A pulchellus
A. pulchellus
1
A richardii
A. richardii
1
A sagrei
A. sagrei
2 20  32 22
A stratulus
A. stratulus
A trinitatis
A. trinitatis
2  50
A wattsi
A. wattsi
1

Thanks in advance. I think this is a great blog and I hope to post something more interesting on here soon.