Tag Archives: egg

JMIH 2017: Brown Anole Reproductive Output Varies Seasonally

TMitchell_JMIH2017

Tim Mitchell, Josh Hall, and Daniel Warner: Seasonal Shifts in Anolis sagrei Reproduction Invoke Challenges for Scientific Reproducibility

Sometimes a scientist just needs hundreds of hatchling anoles for an experiment. Tim Mitchell found himself in this position recently, and, like a good lizard ecologist, he started breeding colonies of anoles in the lab to produce eggs to incubate until hatching. As he created three different breeding colonies from brown anoles (Anolis sagrei) in central Florida, one each in February, June, and September, Tim found that he had also created an ideal situation in which to examine how the reproductive condition and output of brown anoles varies across the breeding season.

Tim, along with his coauthors Josh Hall and Dan Warner, found that females produced eggs with significantly greater mass later in the breeding season. These eggs took longer to produce than those earlier in the year (a greater interclutch interval), and the eggs resulted in hatchlings that had higher mass in relation to the weight of their eggs. These reproductive differences remained even after accounting for the fact that female anoles were also larger and heavier later in the year.

These findings suggest that female A. sagrei may shift their reproductive effort from producing a higher quantity of eggs (i.e., more, smaller eggs resulting in smaller hatchlings) in the beginning of the breeding season, to producing higher quality eggs (i.e., fewer, larger eggs resulting in larger offspring) later in the breeding season. Tim’s findings also stress the importance of investigating and accounting for seasonal differences when examining reproductive output in lizards.

 

The Lichen Anole and Evidence for Parental Care

During an excursion with Indigo Expeditions to Estación Biológica Las Guacamayas, Parque Nacional Laguna del Tigre, Guatemala, we observed the unusual behaviour of a female Lichen Anole Anolis beckeri (previously Anolis/Norops pentaprion), a rarely-studied, canopy-dwelling, anole from Central America. In a paper  in Mesoamerican Herpetology, we report on observing a female A. beckeri potentially tending and guarding eggs. This is possibly also an example of oviposition site fidelity in an anole.

Figure 1

Seven Anolis beckeri deposited in the base of a Bromeliad. Photo: Kimberley Carter

Seven unknown lizard eggs were first discovered on 9th July 2015. The eggs were deposited in the leaves of a bromeliad plant (Bromelia sp.) roughly 5m above the ground. The lichen anole is typically a canopy-dwelling species but, luckily for us, the bromeliad was in a tree at eye level to one of the research station’s balconies! The bromeliad plant had collected water and one egg in particular, lying partially submerged, was a brown, speckled colour. Another of the eggs appeared indented, a sign of potential imminent hatching. The female A. beckeri deposited an additional egg after our return to the UK, which reflects similar egg laying pattern for Anolis where independent, single eggs are laid every 5–25 days during the breeding season (Losos, 2009).

Over the next few days there were no changes in the eggs’ shapes or colour. It wasn’t until 3 days later, on the 12th of July, that we finally witnessed the owner of these eggs: a female A. beckeri sat above the clutch on one of the fronds of the bromeliad. The anole was seen repeatedly climbing into the bromeliad, seemingly to examine the eggs. She would then lick them and exhale heavily over them (perhaps to increase airflow?), before retreating to the top of the bromeliad. She repeated this sequence of behaviours, retreating to safety up the tree and then re-emerging to check on the eggs numerous times.

Figure 2aFigure 2b

Video stills of the female Anolis beckeri tending the eggs. Photos: Kimberley Carter

Video stills of the female Anolis beckeri tending the eggs. Photos: Kimberley Carter

We recorded these behaviours on video and in photographs from a distance, to avoid disturbing the lizard. The female returned on numerous occasions to examine, lick and ‘aerate’ the eggs or to seemingly guard the eggs over the next few days but on the 14th of July the female only monitored the eggs from a distance of ca. 30 cm away and did not approach them.

We also witnessed potential predatory behaviour from a Mexican Parrot Snake (Leptophis mexicanus), On the 15th July the snake was seen in the vicinity of the clutch, perhaps attempting to prey on the adult female. See full paper for detail.

These observations offer insight into the life history and behaviour of this rarely-seen anole species. Hopefully, with the continued work of Indigo Expeditions and the guides at Estación Biológica Las Guacamayas we’ll learn more about these interesting reproductive behaviours in the future.

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.

Baby Anoles – Cute, Cuddly, and Easily Staged!

Check out this piece in the New Scientist, which picked up on our images of Anolis embryos and Thom’s awesome research!

Embryo of Anolis longitibialis, a trunk-ground anole from the Dominican Republic.

The readers of this blog do not need to be convinced that anoles are an amazing model system in evolutionary biology. New and exciting research often finds its way to the Anole Annals. Here we’ve learned about emerging trends in Anolis genomics, speciation, and comparative phylogenetics, to list just a few. In recent years, Anolis has also become a model system for developmental biology. For example, a recent study by Dr. Thom Sanger demonstrated that the diversity of limb dimensions among ecomorphs have evolved from similar developmental mechanisms.

This summer I worked a bit with Thom to learn how to stage Anolis embryos using his handy staging series as a guide. The goal of the project was to determine the stage at which female anoles laid eggs under two treatment conditions – a hot treatment (32°C) and a cold treatment (20°C). I had females from three populations of A. cybotes (55, 700, and 1400 meters in elevation), one population of A. shrevei (2450 m), and one population of A. longitibialis (100m). Unfortunately, I was unable to collect very many eggs despite letting the experiment run for six weeks. I did, however, manage to get several beautiful embryos, which I have imaged and staged. Here I’ll provide some pictures and give a few shorthand methods for staging Anolis embryos.

Continue reading Baby Anoles — Cute, Cuddly, and Easily Staged!

Jack Frost Nipping At My Embryos

My first thawed hatchling, Mr. Freeze, moments after emerging with the desire to rule the world (as soon as he got a little extra warmth from my finger)

Two weeks ago our building decided to test its emergency power generators.  They assured us there should be no problems (never the case) and that electronics plugged into emergency wall sockets shouldn’t have a disruption in power while others might experience small outages that evening.

We assumed our incubator was in the emergency socket and had little concern to think that any disruption to power would cause problems.  Needless to say, that was not the case.  There was a surge when the power came on and according to the repair tech it fried 2 boards… however when power was restored instead of returning to its preset temp, room temp, or even remaining off, it decided to turn on and drop the temp to freezing (or below) (we are unsure of the exact temp as the display board was one of the 2 that fried).  Everything inside was covered in frost and ice including the few remaining eggs I decided to spare from embryo extractions and allow to hatch for breeding next year. Continue reading Jack Frost Nipping At My Embryos