Niche Differences in Coexisting Species: Ecological Insights Into the Role of Activity Patterns, Space Use, and Environmental Preferences

Abstract

The differences in niche structure enable the coexistence of ecologically similar species by reducing direct competition, combining spatial and temporal segregation with phenotypic variation that influences the differential use of resources and habitats. In this study, we examined niche differences in two coexisting green lizard species, Timon lepidus and Lacerta schreiberi, in northern Portugal. Both species differ in body size and habitat preferences, providing an excellent model to investigate mechanisms of niche differentiation. We integrated field observations on environmental variables (temperature, humidity, and illumination), body temperatures, microhabitat use, and activity patterns to complement previously published experimental results on mechanisms of species coexistence. Our observations revealed that T. lepidus prefers drier, rocky, and open areas and human-built structures, while L. schreiberi was predominantly found in moist microhabitats with dense vegetation. Additionally, we detected differences in activity patterns, where T. lepidus displayed unimodal activity peaks around midday, while L. schreiberi exhibited bimodal patterns with activity peaks in the afternoon. These field-derived patterns of microhabitat use and activity patterns were congruent with the thermal and water balance preferences of the two species quantified through previously published experimental trials. Spatial and temporal variations-particularly microhabitat relative humidity and time of activity-were found to be key factors in niche differences.

Keywords: green lizards; microclimatic preferences; microhabitat use; species coexistence; temporal and spatial differences.

FIGURE 1

Percentage of observations during the sampling period (A), field body temperatures (B) and relative humidity (C) for T. lepidus (blue) and L. schreiberi (green) during the entire sampling period. Bars represent the percentage of individuals per bin. Red dashed and dotted lines indicate the mean for T. lepidus and L. schreiberi, respectively; black dashed and dotted lines indicate the corresponding medians. 100% of the observations in (B) and (C) correspond to the sum of all bins.

FIGURE 2

Substrate microhabitat temperature (A), relative humidity (B), body temperature (C), and illuminance (D) for T. lepidus and L. schreiberi in herbaceous vegetation and rocky substrate across different months (May–July).

FIGURE 3

Behaviour and environmental conditions of T. lepidus and L. schreiberi over time. Percentage distribution of behaviours observed for. T. lepidus (right) and L. schreiberi (left) from January to July (A). Behaviours include basking, fleeing, foraging, mating, and sheltering. Air temperature (B), relative humidity (C), illuminance (D), and body temperature associated with each behaviour (E). The blue and green boxplots represent T. lepidus and L. schreiberi, respectively.

FIGURE 4

Boxplots of variables during the sampling period related to the observations of T. lepidus (blue) and L. schreiberi (green) and air temperature (A), relative humidity (B), illuminance (C), and body temperature (D).

FIGURE 5

Activity patterns of Timon lepidus (blue) (A) and Lacerta schreiberi (green) (B), and overlap (blue‐grey shaded area) between species for general activity patterns (C), spring activity patterns (D), and summer activity patterns (E).

FIGURE 6

Spatial distribution and density of observations of T. lepidus and L. schreiberi in the study area. (A) Distribution of observation points for T. lepidus (blue points) and L. schreiberi (green points) along the coastal and inland areas in Castro de São Paio. The inset map shows the location of the study area near Porto, Portugal. (B) Kernel density estimation (KDE) map showing the density of occurrences for both species. Areas with higher densities are indicated by warmer colours, red and yellow for L. schreiberi and blue and purple for T. lepidus .

FIGURE A1

Representative photographs used for individual identification. (A, D, G, J) Dorsal views of individuals and zoomed‐in views of unique dorsal patterns. (B, C, E, F, H, I) Lateral views of head colouration, scale pattern, and morphological features aiding in sex determination and individual recognition. (K) Confirmation of sex by eversion of hemipenes in individuals lacking clear external sexual characteristics. (L) Habitat photo including a scale reference, used for body size estimation of non‐captured individuals.

FIGURE A2

Microhabitats most commonly used by the two species of Mediterranean green lizards in Castro de São Paio. (A–C) Timon lepidus, (D–F) Lacerta schreiberi.

FIGURE A3

Mean air temperature (dashed lines) (A) and mean relative humidity (solid lines) (B) during the sampling period.

FIGURE A4

Field body Temperature (Tb) of L. schreiberi (green) and T. lepidus (blue). Each box represents the interquartile range with the median value indicated by a thick horizontal line inside the box. Outliers are shown as individual points. The black dots represent the mean body temperatures for each time period.