Haematology and biochemistry of the San Cristóbal Lava Lizard (Microlophus bivittatus)

Abstract

The San Cristóbal lava lizard, Microlophus bivittatus, is one of nine species of lava lizards endemic to the Galápagos Islands of Ecuador. No information presently exists about baseline health parameters for any of these species. We analysed blood samples drawn from 47 lizards (25 males and 22 females) captured at two locations on San Cristóbal Island. A portable blood analyser (iSTAT) was used to obtain near-immediate field results for total CO2, lactate, sodium, potassium, ionized calcium, glucose and haemoglobin. Standard laboratory haematology techniques were employed for differential white blood cell counts and haematocrit determination. Body temperature, heart rate and body measurements were also recorded. We found significant differences in haematocrit values between males and females. The values reported in this study provide baseline data that may be useful in detecting changes in health status among lava lizards affected by natural disturbances or anthropogenic threats. Our findings might also be helpful in future efforts to demonstrate associations between specific biochemical or haematological parameters and disease. Because there are several related species on different islands in the Galápagos archipelago, comparisons between populations and species will be of interest. Lay Summary:Haematology and biochemistry values of the San Cristóbal lava lizard Microlophus bivittatus, along with several other health parameters (morphometrics and temperature), are reported for the first time.

Health status of Polychrus gutturosus based on physical examination, hematology and biochemistry parameters in Costa Rica

“… Also depicted are the phylogenetic relationships (adapted from Pyron, Burbrink & Wiens (2013) ) of iguanian families for which hematological information was available. The full name of each species is: Furcifer pardalis (panther chameleon) Laube et al (2016) ; Intellagama lesueurii (Australian water dragon) Johnson et al (2018) ; Microlophus bivittatus (San Cristóbal lava lizard) Arguedas et al (2018) ; Amblyrhynchus cristatus (marine iguana) Lewbart et al (2015) ; Cyclura cychlura (Andros Island iguana) James et al (2006) , Phrynosoma cornutum (Texas horned lizard) McEntire et al (2018) ; Liolaemus wiegmannii (Wiegmann’s lizard) Ceballos de Bruno (1995) and Basiliscus plumifrons (green basilisk) Dallwig et al (2011) . ND = No Data.…”

“… Also depicted are the phylogenetic relationships (adapted from Pyron et al (2013)) of iguanian families for which biochemical information was available. The full name of each species is: Furcifer pardalis (panther chameleon), Intellagama lesueurii (Australian water dragon) Johnson et al (2018) ; Pogona vitticeps (bearded dragon), Microlophus bivittatus (San Cristóbal lava lizard) Arguedas et al (2018) ; Iguana iguana (green iguana) Harr et al (2001) ; Cyclura cychlura (Andros Island iguana); James et al (2006) and Basiliscus plumifrons (green basilisk.) Dallwig et al (2011) .…”

“…Studies evaluating the health status and characteristics of free-ranging populations are, however, scarce or absent for most species, especially those that are rarely seen in the wild ( Bell & Donnelly, 2006 ; Whitfield et al, 2007 ; Dallwig et al, 2011 ). In lizards, health assessments reported in the literature have usually been done on species that are threatened ( Alberts et al, 1998 ; Espinosa-Avilés, Salomón-Soto & Morales-Martínez, 2008 ; McEntire et al, 2018 ), endemic ( Lewbart et al, 2015 ; Arguedas et al, 2018 ), or kept in captivity ( Ellman, 1997 ; Mayer et al, 2005 ; Laube et al, 2016 ), providing information on the survival of species with conservation issues. However, free-ranging species with no apparent threats have generally not been evaluated as well.…”

Supplemental Information 2: Raw data.

“…In other iguanian lizards where males are larger than females, significative differences in biochemical values have been found between sexes (Dallwig et al, 2011). For example, males of the San Cristóbal lava lizard (Microlophus bivittatus) had higher hemoglobin, PCV and glucose than females (Arguedas et al, 2018), and female green iguanas (Iguana iguana) had higher hemoglobin and PCV than males (Harr et al, 2001). Interestingly, in Phrynosoma cornutum, where females are larger than males, basophil counts were lower in females than in males (McEntire et al, 2018).…”

“…Studies evaluating the health status and characteristics of free-ranging populations are, however, scarce or absent for most species, especially those that are rarely seen in the wild (Bell & Donnelly, 2006;Whitfield et al, 2007;Dallwig et al, 2011). In lizards, health assessments reported in the literature have usually been done on species that are threatened (Alberts et al, 1998;Espinosa-Avilés, Salomón-Soto & Morales-Martínez, 2008;McEntire et al, 2018), endemic (Lewbart et al, 2015;Arguedas et al, 2018), or kept in captivity (Ellman, 1997;Mayer et al, 2005;Laube et al, 2016), providing information on the survival of species with conservation issues. However, free-ranging species with no apparent threats have generally not been evaluated as well.…”