You can always use the proper WordPress Ajax API (well not really an api)
for example:
<li><a href="https://wordpress.stackexchange.com/questions/25857/url to wp-admin/admin-ajax.php?action=my_ajax_tabs&tab=tab1">Tab 1</a></li>
<li><a href="url to wp-admin/admin-ajax.php?action=my_ajax_tabs&tab=tab2">Tab 2</a></li>
then you create a function that will respond to the ajax calls:
function do_my_tabs(){
$tab = $_GET['tab'];
switch ($tab){
case "tab1":
echo 'tab1 content';
break;
case "tab2":
echo 'tab2 content';
break;
}
die();
}
and last just hook this function :
//if you want only logged in users to access this function use this hook
add_action('wp_ajax_my_ajax_tabs', 'do_my_tabs');
//if you want none logged in users to access this function use this hook
add_action('wp_ajax_nopriv_my_ajax_tabs', 'do_my_tabs');
//if you want both logged in users and guests to access this function then add both